Revert of Oilpan: Use weak pointers in StyleSheetContents caches....

Revert of Oilpan: Use weak pointers in StyleSheetContents caches. (https://codereview.chromium.org/185403016/)

Reason for revert:
This patch seems to have made a number of layout tests fail on the oilpan bots. Reverting while I investigate.

Original issue's description:
> Oilpan: Use weak pointers in StyleSheetContents caches.
> 
> This fixes use-after-free that could occur when StyleSheetContents
> dies when an allocation happens during insertion of a new
> StyleSheetContents. Using the built-in weak processing this will
> not happen because the iterator used during insertion will keep
> the StyleSheetContents alive.
> 
> R=erik.corry@gmail.com, haraken@chromium.org, vegorov@chromium.org
> NOTRY=true
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=168444

TBR=erik.corry@gmail.com,haraken@chromium.org,vegorov@chromium.org,zerny@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/187473003

git-svn-id: svn://svn.chromium.org/blink/trunk@168458 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/css/StyleSheetContents.cpp

@@ -97,8 +97,8 @@ StyleSheetContents::StyleSheetContents(const StyleSheetContents& o)
 
 StyleSheetContents::~StyleSheetContents()
 {
-#if !ENABLE(OILPAN)
     StyleEngine::removeSheet(this);
+#if !ENABLE(OILPAN)
     clearRules();
 #endif
 }

third_party/WebKit/Source/core/dom/StyleEngine.cpp

@@ -54,28 +54,18 @@ namespace WebCore {
 
 using namespace HTMLNames;
 
-static WillBeHeapHashMap<AtomicString, RawPtrWillBeWeakMember<StyleSheetContents> >& textToSheetCache()
+static HashMap<AtomicString, StyleSheetContents*>& textToSheetCache()
 {
-    typedef WillBeHeapHashMap<AtomicString, RawPtrWillBeWeakMember<StyleSheetContents> > TextToSheetCache;
-#if ENABLE(OILPAN)
-    DEFINE_STATIC_LOCAL(Persistent<TextToSheetCache>, cache, (new TextToSheetCache));
-    return *cache;
-#else
+    typedef HashMap<AtomicString, StyleSheetContents*> TextToSheetCache;
     DEFINE_STATIC_LOCAL(TextToSheetCache, cache, ());
     return cache;
-#endif
 }
 
-static WillBeHeapHashMap<RawPtrWillBeWeakMember<StyleSheetContents>, AtomicString>& sheetToTextCache()
+static HashMap<StyleSheetContents*, AtomicString>& sheetToTextCache()
 {
-    typedef WillBeHeapHashMap<RawPtrWillBeWeakMember<StyleSheetContents>, AtomicString> SheetToTextCache;
-#if ENABLE(OILPAN)
-    DEFINE_STATIC_LOCAL(Persistent<SheetToTextCache>, cache, (new SheetToTextCache));
-    return *cache;
-#else
+    typedef HashMap<StyleSheetContents*, AtomicString> SheetToTextCache;
     DEFINE_STATIC_LOCAL(SheetToTextCache, cache, ());
     return cache;
-#endif
 }
 
 StyleEngine::StyleEngine(Document& document)
@@ -589,7 +579,7 @@ PassRefPtr<CSSStyleSheet> StyleEngine::createSheet(Element* e, const String& tex
     if (!e->document().inQuirksMode()) {
         AtomicString textContent(text);
 
-        WillBeHeapHashMap<AtomicString, RawPtrWillBeWeakMember<StyleSheetContents> >::AddResult result = textToSheetCache().add(textContent, RawPtrWillBeWeakMember<StyleSheetContents>(nullptr));
+        HashMap<AtomicString, StyleSheetContents*>::AddResult result = textToSheetCache().add(textContent, 0);
         if (result.isNewEntry || !result.storedValue->value) {
             styleSheet = StyleEngine::parseSheet(e, text, startPosition, createdByParser);
             if (result.isNewEntry && styleSheet->contents()->maybeCacheable()) {
@@ -620,7 +610,7 @@ PassRefPtr<CSSStyleSheet> StyleEngine::parseSheet(Element* e, const String& text
 
 void StyleEngine::removeSheet(StyleSheetContents* contents)
 {
-    WillBeHeapHashMap<RawPtrWillBeWeakMember<StyleSheetContents>, AtomicString>::iterator it = sheetToTextCache().find(contents);
+    HashMap<StyleSheetContents*, AtomicString>::iterator it = sheetToTextCache().find(contents);
     if (it == sheetToTextCache().end())
         return;