Rename StyleSheetCollections to StyleEngine.

Source/core/page/PageGroup.cpp

Index: Source/core/page/PageGroup.cpp
diff --git a/Source/core/page/PageGroup.cpp b/Source/core/page/PageGroup.cpp
index abe982a92a300a41a16bea6e9a3f19d2878b3f22..29b1937fac13b868c6ca5004c6305d4dafddc083 100644
--- a/Source/core/page/PageGroup.cpp
+++ b/Source/core/page/PageGroup.cpp
@@ -27,7 +27,7 @@
 #include "core/page/PageGroup.h"
 
 #include "core/dom/Document.h"
-#include "core/dom/StyleSheetCollections.h"
+#include "core/dom/StyleEngine.h"
 #include "core/page/Frame.h"
 #include "core/page/Page.h"
 
@@ -92,7 +92,7 @@ void PageGroup::invalidatedInjectedStyleSheetCacheInAllFrames()
     HashSet<Page*>::const_iterator end = m_pages.end();
     for (HashSet<Page*>::const_iterator it = m_pages.begin(); it != end; ++it) {
         for (Frame* frame = (*it)->mainFrame(); frame; frame = frame->tree()->traverseNext())
-            frame->document()->styleSheetCollections()->invalidateInjectedStyleSheetCache();
+            frame->document()->styleEngine()->invalidateInjectedStyleSheetCache();
     }
 }