Move the Widget hierarchy to the Oilpan heap.

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index cc51ccafd7333114df2d8a77a49dd347839422df..64597aca002b7bdb3bbda792e3284c9ffb02653f 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -1914,7 +1914,7 @@ void Document::updateLayout()
 
     ScriptForbiddenScope forbidScript;
 
-    RefPtr<FrameView> frameView = view();
+    RefPtrWillBeRawPtr<FrameView> frameView = view();
     if (frameView && frameView->isInPerformLayout()) {
         // View layout should not be re-entrant.
         ASSERT_NOT_REACHED();