[CLEANUP] Rector: Add strict return type based on returned strict expr type (#581)

This applies the rule ReturnTypeFromStrictBoolReturnExprRector. For
Details see:
https://github.com/rectorphp/rector/blob/main/docs/rector_rules_overview.md#returntypefromstrictboolreturnexprrector

Signed-off-by: Daniel Ziegenberg <[email protected]>

Author: ziegenberg

src/CSSList/AtRuleBlockList.php

@@ -74,10 +74,7 @@ public function render(OutputFormat $oOutputFormat)
         return $sResult;
     }
 
-    /**
-     * @return bool
-     */
-    public function isRootList()
+    public function isRootList(): bool
     {
         return false;
     }

src/CSSList/Document.php

@@ -155,10 +155,7 @@ public function render(OutputFormat $oOutputFormat = null)
         return $oOutputFormat->comments($this) . $this->renderListContents($oOutputFormat);
     }
 
-    /**
-     * @return bool
-     */
-    public function isRootList()
+    public function isRootList(): bool
     {
         return true;
     }

src/CSSList/KeyFrame.php

@@ -79,10 +79,7 @@ public function render(OutputFormat $oOutputFormat)
         return $sResult;
     }
 
-    /**
-     * @return bool
-     */
-    public function isRootList()
+    public function isRootList(): bool
     {
         return false;
     }

src/Parsing/ParserState.php

@@ -427,10 +427,8 @@ private function inputLeft()
      * @param string $sString1
      * @param string $sString2
      * @param bool $bCaseInsensitive
-     *
-     * @return bool
      */
-    public function streql($sString1, $sString2, $bCaseInsensitive = true)
+    public function streql($sString1, $sString2, $bCaseInsensitive = true): bool
     {
         if ($bCaseInsensitive) {
             return $this->strtolower($sString1) === $this->strtolower($sString2);

src/RuleSet/DeclarationBlock.php

@@ -129,10 +129,8 @@ public function setSelectors($mSelector, $oList = null)
      * Remove one of the selectors of the block.
      *
      * @param Selector|string $mSelector
-     *
-     * @return bool
      */
-    public function removeSelector($mSelector)
+    public function removeSelector($mSelector): bool
     {
         if ($mSelector instanceof Selector) {
             $mSelector = $mSelector->getSelector();

src/Value/Size.php

@@ -187,10 +187,7 @@ public function isSize()
         return !$this->isColorComponent();
     }
 
-    /**
-     * @return bool
-     */
-    public function isRelative()
+    public function isRelative(): bool
     {
         if (in_array($this->sUnit, self::RELATIVE_SIZE_UNITS, true)) {
             return true;