diff --git a/framework/yii/db/ActiveQuery.php b/framework/yii/db/ActiveQuery.php
index 21f2f67..48af835 100644
--- a/framework/yii/db/ActiveQuery.php
+++ b/framework/yii/db/ActiveQuery.php
@@ -168,7 +168,7 @@ class ActiveQuery extends Query
 	/**
 	 * Sets the [[asArray]] property.
 	 * @param boolean $value whether to return the query results in terms of arrays instead of Active Records.
-	 * @return ActiveQuery the query object itself
+	 * @return static the query object itself
 	 */
 	public function asArray($value = true)
 	{
@@ -196,7 +196,7 @@ class ActiveQuery extends Query
 	 * ))->all();
 	 * ~~~
 	 *
-	 * @return ActiveQuery the query object itself
+	 * @return static the query object itself
 	 */
 	public function with()
 	{
@@ -223,12 +223,11 @@ class ActiveQuery extends Query
 	 * }
 	 * ~~~
 	 *
-	 * @return ActiveQuery the query object itself
+	 * @return static the query object itself
 	 */
 	public function indexBy($column)
 	{
-		$this->indexBy = $column;
-		return $this;
+		parent::indexBy($column);
 	}
 
 	private function createModels($rows)
diff --git a/framework/yii/db/ActiveRelation.php b/framework/yii/db/ActiveRelation.php
index f05c56a..c1c8b2d 100644
--- a/framework/yii/db/ActiveRelation.php
+++ b/framework/yii/db/ActiveRelation.php
@@ -66,7 +66,7 @@ class ActiveRelation extends ActiveQuery
 	 * @param string $relationName the relation name. This refers to a relation declared in [[primaryModel]].
 	 * @param callable $callable a PHP callback for customizing the relation associated with the pivot table.
 	 * Its signature should be `function($query)`, where `$query` is the query to be customized.
-	 * @return ActiveRelation the relation object itself.
+	 * @return static the relation object itself.
 	 */
 	public function via($relationName, $callable = null)
 	{
@@ -86,7 +86,7 @@ class ActiveRelation extends ActiveQuery
 	 * in the [[primaryModel]] table.
 	 * @param callable $callable a PHP callback for customizing the relation associated with the pivot table.
 	 * Its signature should be `function($query)`, where `$query` is the query to be customized.
-	 * @return ActiveRelation
+	 * @return static
 	 */
 	public function viaTable($tableName, $link, $callable = null)
 	{
diff --git a/framework/yii/db/Command.php b/framework/yii/db/Command.php
index bfb8a26..73ac04b 100644
--- a/framework/yii/db/Command.php
+++ b/framework/yii/db/Command.php
@@ -88,7 +88,7 @@ class Command extends \yii\base\Component
 	 * Specifies the SQL statement to be executed.
 	 * The previous SQL execution (if any) will be cancelled, and [[params]] will be cleared as well.
 	 * @param string $sql the SQL statement to be set.
-	 * @return Command this command instance
+	 * @return static this command instance
 	 */
 	public function setSql($sql)
 	{
@@ -174,7 +174,7 @@ class Command extends \yii\base\Component
 	 * @param integer $dataType SQL data type of the parameter. If null, the type is determined by the PHP type of the value.
 	 * @param integer $length length of the data type
 	 * @param mixed $driverOptions the driver-specific options
-	 * @return Command the current command being executed
+	 * @return static the current command being executed
 	 * @see http://www.php.net/manual/en/function.PDOStatement-bindParam.php
 	 */
 	public function bindParam($name, &$value, $dataType = null, $length = null, $driverOptions = null)
@@ -201,7 +201,7 @@ class Command extends \yii\base\Component
 	 * placeholders, this will be the 1-indexed position of the parameter.
 	 * @param mixed $value The value to bind to the parameter
 	 * @param integer $dataType SQL data type of the parameter. If null, the type is determined by the PHP type of the value.
-	 * @return Command the current command being executed
+	 * @return static the current command being executed
 	 * @see http://www.php.net/manual/en/function.PDOStatement-bindValue.php
 	 */
 	public function bindValue($name, $value, $dataType = null)
@@ -225,7 +225,7 @@ class Command extends \yii\base\Component
 	 * e.g. `array(':name' => 'John', ':age' => 25)`. By default, the PDO type of each value is determined
 	 * by its PHP type. You may explicitly specify the PDO type by using an array: `array(value, type)`,
 	 * e.g. `array(':name' => 'John', ':profile' => array($profile, \PDO::PARAM_LOB))`.
-	 * @return Command the current command being executed
+	 * @return static the current command being executed
 	 */
 	public function bindValues($values)
 	{
diff --git a/framework/yii/db/Query.php b/framework/yii/db/Query.php
index d1e7864..dbe0424 100644
--- a/framework/yii/db/Query.php
+++ b/framework/yii/db/Query.php
@@ -166,7 +166,7 @@ class Query extends Component
 	 * }
 	 * ~~~
 	 *
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 */
 	public function indexBy($column)
 	{
@@ -325,7 +325,7 @@ class Query extends Component
 	 * (which means the column contains a DB expression).
 	 * @param string $option additional option that should be appended to the 'SELECT' keyword. For example,
 	 * in MySQL, the option 'SQL_CALC_FOUND_ROWS' can be used.
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 */
 	public function select($columns, $option = null)
 	{
@@ -340,7 +340,7 @@ class Query extends Component
 	/**
 	 * Sets the value indicating whether to SELECT DISTINCT or not.
 	 * @param bool $value whether to SELECT DISTINCT or not.
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 */
 	public function distinct($value = true)
 	{
@@ -355,7 +355,7 @@ class Query extends Component
 	 * Table names can contain schema prefixes (e.g. `'public.tbl_user'`) and/or table aliases (e.g. `'tbl_user u'`).
 	 * The method will automatically quote the table names unless it contains some parenthesis
 	 * (which means the table is given as a sub-query or DB expression).
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 */
 	public function from($tables)
 	{
@@ -431,7 +431,7 @@ class Query extends Component
 	 *
 	 * @param string|array $condition the conditions that should be put in the WHERE part.
 	 * @param array $params the parameters (name => value) to be bound to the query.
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 * @see andWhere()
 	 * @see orWhere()
 	 */
@@ -448,7 +448,7 @@ class Query extends Component
 	 * @param string|array $condition the new WHERE condition. Please refer to [[where()]]
 	 * on how to specify this parameter.
 	 * @param array $params the parameters (name => value) to be bound to the query.
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 * @see where()
 	 * @see orWhere()
 	 */
@@ -469,7 +469,7 @@ class Query extends Component
 	 * @param string|array $condition the new WHERE condition. Please refer to [[where()]]
 	 * on how to specify this parameter.
 	 * @param array $params the parameters (name => value) to be bound to the query.
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 * @see where()
 	 * @see andWhere()
 	 */
@@ -560,7 +560,7 @@ class Query extends Component
 	 * Columns can be specified in either a string (e.g. "id, name") or an array (e.g. array('id', 'name')).
 	 * The method will automatically quote the column names unless a column contains some parenthesis
 	 * (which means the column contains a DB expression).
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 * @see addGroupBy()
 	 */
 	public function groupBy($columns)
@@ -578,7 +578,7 @@ class Query extends Component
 	 * Columns can be specified in either a string (e.g. "id, name") or an array (e.g. array('id', 'name')).
 	 * The method will automatically quote the column names unless a column contains some parenthesis
 	 * (which means the column contains a DB expression).
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 * @see groupBy()
 	 */
 	public function addGroupBy($columns)
@@ -599,7 +599,7 @@ class Query extends Component
 	 * @param string|array $condition the conditions to be put after HAVING.
 	 * Please refer to [[where()]] on how to specify this parameter.
 	 * @param array $params the parameters (name => value) to be bound to the query.
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 * @see andHaving()
 	 * @see orHaving()
 	 */
@@ -616,7 +616,7 @@ class Query extends Component
 	 * @param string|array $condition the new HAVING condition. Please refer to [[where()]]
 	 * on how to specify this parameter.
 	 * @param array $params the parameters (name => value) to be bound to the query.
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 * @see having()
 	 * @see orHaving()
 	 */
@@ -637,7 +637,7 @@ class Query extends Component
 	 * @param string|array $condition the new HAVING condition. Please refer to [[where()]]
 	 * on how to specify this parameter.
 	 * @param array $params the parameters (name => value) to be bound to the query.
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 * @see having()
 	 * @see andHaving()
 	 */
@@ -659,7 +659,7 @@ class Query extends Component
 	 * (e.g. `array('id' => Query::SORT_ASC, 'name' => Query::SORT_DESC)`).
 	 * The method will automatically quote the column names unless a column contains some parenthesis
 	 * (which means the column contains a DB expression).
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 * @see addOrderBy()
 	 */
 	public function orderBy($columns)
@@ -675,7 +675,7 @@ class Query extends Component
 	 * (e.g. `array('id' => Query::SORT_ASC, 'name' => Query::SORT_DESC)`).
 	 * The method will automatically quote the column names unless a column contains some parenthesis
 	 * (which means the column contains a DB expression).
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 * @see orderBy()
 	 */
 	public function addOrderBy($columns)
@@ -710,7 +710,7 @@ class Query extends Component
 	/**
 	 * Sets the LIMIT part of the query.
 	 * @param integer $limit the limit. Use null or negative value to disable limit.
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 */
 	public function limit($limit)
 	{
@@ -721,7 +721,7 @@ class Query extends Component
 	/**
 	 * Sets the OFFSET part of the query.
 	 * @param integer $offset the offset. Use null or negative value to disable offset.
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 */
 	public function offset($offset)
 	{
@@ -732,7 +732,7 @@ class Query extends Component
 	/**
 	 * Appends a SQL statement using UNION operator.
 	 * @param string|Query $sql the SQL statement to be appended using UNION
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 */
 	public function union($sql)
 	{
@@ -744,7 +744,7 @@ class Query extends Component
 	 * Sets the parameters to be bound to the query.
 	 * @param array $params list of query parameter values indexed by parameter placeholders.
 	 * For example, `array(':name' => 'Dan', ':age' => 31)`.
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 * @see addParams()
 	 */
 	public function params($params)
@@ -757,7 +757,7 @@ class Query extends Component
 	 * Adds additional parameters to be bound to the query.
 	 * @param array $params list of query parameter values indexed by parameter placeholders.
 	 * For example, `array(':name' => 'Dan', ':age' => 31)`.
-	 * @return Query the query object itself
+	 * @return static the query object itself
 	 * @see params()
 	 */
 	public function addParams($params)
diff --git a/framework/yii/gii/components/ActiveField.php b/framework/yii/gii/components/ActiveField.php
index 6a67217..8bb67a9 100644
--- a/framework/yii/gii/components/ActiveField.php
+++ b/framework/yii/gii/components/ActiveField.php
@@ -32,6 +32,10 @@ class ActiveField extends \yii\widgets\ActiveField
 		}
 	}
 
+	/**
+	 * Makes filed remember its value between page reloads
+	 * @return static the field object itself
+	 */
 	public function sticky()
 	{
 		$this->options['class'] .= ' sticky';
diff --git a/framework/yii/requirements/YiiRequirementChecker.php b/framework/yii/requirements/YiiRequirementChecker.php
index 7d5ae42..c8ad45d 100644
--- a/framework/yii/requirements/YiiRequirementChecker.php
+++ b/framework/yii/requirements/YiiRequirementChecker.php
@@ -63,7 +63,7 @@ class YiiRequirementChecker
 	 * @param array|string $requirements requirements to be checked.
 	 * If an array, it is treated as the set of requirements;
 	 * If a string, it is treated as the path of the file, which contains the requirements;
-	 * @return YiiRequirementChecker self instance.
+	 * @return static self instance.
 	 */
 	function check($requirements)
 	{
diff --git a/framework/yii/web/HeaderCollection.php b/framework/yii/web/HeaderCollection.php
index 609058b..a729f6b 100644
--- a/framework/yii/web/HeaderCollection.php
+++ b/framework/yii/web/HeaderCollection.php
@@ -83,7 +83,7 @@ class HeaderCollection extends Object implements \IteratorAggregate, \ArrayAcces
 	 * If there is already a header with the same name, it will be replaced.
 	 * @param string $name the name of the header
 	 * @param string $value the value of the header
-	 * @return HeaderCollection the collection object itself
+	 * @return static the collection object itself
 	 */
 	public function set($name, $value = '')
 	{
@@ -98,7 +98,7 @@ class HeaderCollection extends Object implements \IteratorAggregate, \ArrayAcces
 	 * be appended to it instead of replacing it.
 	 * @param string $name the name of the header
 	 * @param string $value the value of the header
-	 * @return HeaderCollection the collection object itself
+	 * @return static the collection object itself
 	 */
 	public function add($name, $value)
 	{
@@ -112,7 +112,7 @@ class HeaderCollection extends Object implements \IteratorAggregate, \ArrayAcces
 	 * If there is already a header with the same name, the new one will be ignored.
 	 * @param string $name the name of the header
 	 * @param string $value the value of the header
-	 * @return HeaderCollection the collection object itself
+	 * @return static the collection object itself
 	 */
 	public function setDefault($name, $value)
 	{
diff --git a/framework/yii/web/Response.php b/framework/yii/web/Response.php
index f0d506b..703ea6f 100644
--- a/framework/yii/web/Response.php
+++ b/framework/yii/web/Response.php
@@ -605,7 +605,7 @@ class Response extends \yii\base\Response
 	 * @param integer $statusCode the HTTP status code. If null, it will use 302.
 	 * See [[http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html]]
 	 * for details about HTTP status code
-	 * @return Response the response object itself
+	 * @return static the response object itself
 	 */
 	public function redirect($url, $statusCode = null)
 	{
diff --git a/framework/yii/widgets/ActiveField.php b/framework/yii/widgets/ActiveField.php
index 7df67fa..d31c50b 100644
--- a/framework/yii/widgets/ActiveField.php
+++ b/framework/yii/widgets/ActiveField.php
@@ -221,7 +221,7 @@ class ActiveField extends Component
 	 * @param array $options the tag options in terms of name-value pairs. It will be merged with [[labelOptions]].
 	 * The options will be rendered as the attributes of the resulting tag. The values will be HTML-encoded
 	 * using [[Html::encode()]]. If a value is null, the corresponding attribute will not be rendered.
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function label($label = null, $options = array())
 	{
@@ -244,7 +244,7 @@ class ActiveField extends Component
 	 *
 	 * - tag: this specifies the tag name. If not set, "div" will be used.
 	 *
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function error($options = array())
 	{
@@ -263,7 +263,7 @@ class ActiveField extends Component
 	 *
 	 * - tag: this specifies the tag name. If not set, "div" will be used.
 	 *
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function hint($content, $options = array())
 	{
@@ -278,7 +278,7 @@ class ActiveField extends Component
 	 * @param string $type the input type (e.g. 'text', 'password')
 	 * @param array $options the tag options in terms of name-value pairs. These will be rendered as
 	 * the attributes of the resulting tag. The values will be HTML-encoded using [[Html::encode()]].
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function input($type, $options = array())
 	{
@@ -293,7 +293,7 @@ class ActiveField extends Component
 	 * unless they are explicitly specified in `$options`.
 	 * @param array $options the tag options in terms of name-value pairs. These will be rendered as
 	 * the attributes of the resulting tag. The values will be HTML-encoded using [[Html::encode()]].
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function textInput($options = array())
 	{
@@ -308,7 +308,7 @@ class ActiveField extends Component
 	 * unless they are explicitly specified in `$options`.
 	 * @param array $options the tag options in terms of name-value pairs. These will be rendered as
 	 * the attributes of the resulting tag. The values will be HTML-encoded using [[Html::encode()]].
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function passwordInput($options = array())
 	{
@@ -323,7 +323,7 @@ class ActiveField extends Component
 	 * unless they are explicitly specified in `$options`.
 	 * @param array $options the tag options in terms of name-value pairs. These will be rendered as
 	 * the attributes of the resulting tag. The values will be HTML-encoded using [[Html::encode()]].
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function fileInput($options = array())
 	{
@@ -339,7 +339,7 @@ class ActiveField extends Component
 	 * The model attribute value will be used as the content in the textarea.
 	 * @param array $options the tag options in terms of name-value pairs. These will be rendered as
 	 * the attributes of the resulting tag. The values will be HTML-encoded using [[Html::encode()]].
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function textarea($options = array())
 	{
@@ -367,7 +367,7 @@ class ActiveField extends Component
 	 * @param boolean $enclosedByLabel whether to enclose the radio within the label.
 	 * If true, the method will still use [[template]] to layout the checkbox and the error message
 	 * except that the radio is enclosed by the label tag.
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function radio($options = array(), $enclosedByLabel = true)
 	{
@@ -402,7 +402,7 @@ class ActiveField extends Component
 	 * @param boolean $enclosedByLabel whether to enclose the checkbox within the label.
 	 * If true, the method will still use [[template]] to layout the checkbox and the error message
 	 * except that the checkbox is enclosed by the label tag.
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function checkbox($options = array(), $enclosedByLabel = true)
 	{
@@ -448,7 +448,7 @@ class ActiveField extends Component
 	 * The rest of the options will be rendered as the attributes of the resulting tag. The values will
 	 * be HTML-encoded using [[Html::encode()]]. If a value is null, the corresponding attribute will not be rendered.
 	 *
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function dropDownList($items, $options = array())
 	{
@@ -490,7 +490,7 @@ class ActiveField extends Component
 	 * The rest of the options will be rendered as the attributes of the resulting tag. The values will
 	 * be HTML-encoded using [[Html::encode()]]. If a value is null, the corresponding attribute will not be rendered.
 	 *
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function listBox($items, $options = array())
 	{
@@ -522,7 +522,7 @@ class ActiveField extends Component
 	 * where $index is the zero-based index of the checkbox in the whole list; $label
 	 * is the label for the checkbox; and $name, $value and $checked represent the name,
 	 * value and the checked status of the checkbox input.
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function checkboxList($items, $options = array())
 	{
@@ -552,7 +552,7 @@ class ActiveField extends Component
 	 * where $index is the zero-based index of the radio button in the whole list; $label
 	 * is the label for the radio button; and $name, $value and $checked represent the name,
 	 * value and the checked status of the radio button input.
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function radioList($items, $options = array())
 	{
@@ -571,7 +571,7 @@ class ActiveField extends Component
 	 *
 	 * @param string $class the widget class name
 	 * @param array $config name-value pairs that will be used to initialize the widget
-	 * @return ActiveField the field object itself
+	 * @return static the field object itself
 	 */
 	public function widget($class, $config = array())
 	{