Rename StyleSheetCollections to StyleEngine.

Source/web/WebDocument.cpp

Index: Source/web/WebDocument.cpp
diff --git a/Source/web/WebDocument.cpp b/Source/web/WebDocument.cpp
index 9cd6e651dd0c3b6d2869d4257d2f22063759ad3f..4e55b5fb1d9baaf3a310b97c7ac1734811ea7d47 100644
--- a/Source/web/WebDocument.cpp
+++ b/Source/web/WebDocument.cpp
@@ -51,7 +51,7 @@
 #include "core/dom/Element.h"
 #include "core/dom/FullscreenElementStack.h"
 #include "core/dom/NodeList.h"
-#include "core/dom/StyleSheetCollections.h"
+#include "core/dom/StyleEngine.h"
 #include "core/html/HTMLAllCollection.h"
 #include "core/html/HTMLBodyElement.h"
 #include "core/html/HTMLCollection.h"
@@ -208,9 +208,9 @@ void WebDocument::insertUserStyleSheet(const WebString& sourceCode, UserStyleLev
     parsedSheet->setIsUserStyleSheet(styleLevel == UserStyleUserLevel);
     parsedSheet->parseString(sourceCode);
     if (parsedSheet->isUserStyleSheet())
-        document->styleSheetCollections()->addUserSheet(parsedSheet);
+        document->styleEngine()->addUserSheet(parsedSheet);
     else
-        document->styleSheetCollections()->addAuthorSheet(parsedSheet);
+        document->styleEngine()->addAuthorSheet(parsedSheet);
 }
 
 void WebDocument::cancelFullScreen()