Do not zero-initialize RawPtr.

Source/core/dom/StyleEngine.cpp

Index: Source/core/dom/StyleEngine.cpp
diff --git a/Source/core/dom/StyleEngine.cpp b/Source/core/dom/StyleEngine.cpp
index 5524bca66849b0fedbf00a3b8dcaaf63a66cb630..3ddc6cebdb07b5fa0279d56c0e71c8cb7606936c 100644
--- a/Source/core/dom/StyleEngine.cpp
+++ b/Source/core/dom/StyleEngine.cpp
@@ -579,7 +579,7 @@ static bool isCacheableForStyleElement(const StyleSheetContents& contents)
 
 PassRefPtrWillBeRawPtr<CSSStyleSheet> StyleEngine::createSheet(Element* e, const String& text, TextPosition startPosition, bool createdByParser)
 {
-    RefPtrWillBeRawPtr<CSSStyleSheet> styleSheet;
+    RefPtrWillBeRawPtr<CSSStyleSheet> styleSheet = nullptr;
 
     e->document().styleEngine()->addPendingSheet();
 
@@ -612,7 +612,7 @@ PassRefPtrWillBeRawPtr<CSSStyleSheet> StyleEngine::createSheet(Element* e, const
 
 PassRefPtrWillBeRawPtr<CSSStyleSheet> StyleEngine::parseSheet(Element* e, const String& text, TextPosition startPosition, bool createdByParser)
 {
-    RefPtrWillBeRawPtr<CSSStyleSheet> styleSheet;
+    RefPtrWillBeRawPtr<CSSStyleSheet> styleSheet = nullptr;
     styleSheet = CSSStyleSheet::createInline(e, KURL(), startPosition, e->document().inputEncoding());
     styleSheet->contents()->parseStringAtPosition(text, startPosition, createdByParser);
     return styleSheet;