Fix memory error during selector matching due to getMatchedCSSRules.

Source/core/css/CSSStyleSheet.cpp

Index: Source/core/css/CSSStyleSheet.cpp
diff --git a/Source/core/css/CSSStyleSheet.cpp b/Source/core/css/CSSStyleSheet.cpp
index 9737560190271c7ebc8e6aa57ef768b288dd7777..b1ce8d3351a8ccf62e8cb0cc147d706360e1c625 100644
--- a/Source/core/css/CSSStyleSheet.cpp
+++ b/Source/core/css/CSSStyleSheet.cpp
@@ -28,6 +28,7 @@
 #include "core/css/CSSImportRule.h"
 #include "core/css/CSSParser.h"
 #include "core/css/CSSRuleList.h"
+#include "core/css/CSSStyleRule.h"
 #include "core/css/MediaList.h"
 #include "core/css/StyleRule.h"
 #include "core/css/StyleSheetContents.h"
@@ -117,6 +118,9 @@ CSSStyleSheet::~CSSStyleSheet()
         if (m_childRuleCSSOMWrappers[i])
             m_childRuleCSSOMWrappers[i]->setParentStyleSheet(0);
     }
+    for (unsigned i = 0; i < m_extraChildRuleCSSOMWrappers.size(); ++i) {
+        m_extraChildRuleCSSOMWrappers[i]->setParentStyleSheet(0);
+    }
     if (m_mediaCSSOMWrapper)
         m_mediaCSSOMWrapper->clearParentStyleSheet();
 
@@ -164,6 +168,11 @@ void CSSStyleSheet::didMutate(StyleSheetUpdateType updateType)
     owner->modifiedStyleSheet(this, RecalcStyleDeferred, updateMode);
 }
 
+void CSSStyleSheet::registerExtraChildRuleCSSOMWrapper(PassRefPtr<CSSRule> rule)
+{
+    m_extraChildRuleCSSOMWrappers.append(rule);
+}
+
 void CSSStyleSheet::reattachChildRuleCSSOMWrappers()
 {
     for (unsigned i = 0; i < m_childRuleCSSOMWrappers.size(); ++i) {