Move the Widget hierarchy to the Oilpan heap.

Source/core/loader/FrameLoaderClient.h

Index: Source/core/loader/FrameLoaderClient.h
diff --git a/Source/core/loader/FrameLoaderClient.h b/Source/core/loader/FrameLoaderClient.h
index e9d9690b88d2cd9943bda37391143639a782c75d..357345db7d2eb24e9371788c8f5d4bb30054f618 100644
--- a/Source/core/loader/FrameLoaderClient.h
+++ b/Source/core/loader/FrameLoaderClient.h
@@ -149,9 +149,9 @@ namespace blink {
             AllowDetachedPlugin,
         };
         virtual bool canCreatePluginWithoutRenderer(const String& mimeType) const = 0;
-        virtual PassRefPtr<Widget> createPlugin(HTMLPlugInElement*, const KURL&, const Vector<String>&, const Vector<String>&, const String&, bool loadManually, DetachedPluginPolicy) = 0;
+        virtual PassRefPtrWillBeRawPtr<Widget> createPlugin(HTMLPlugInElement*, const KURL&, const Vector<String>&, const Vector<String>&, const String&, bool loadManually, DetachedPluginPolicy) = 0;
 
-        virtual PassRefPtr<Widget> createJavaAppletWidget(HTMLAppletElement*, const KURL& baseURL, const Vector<String>& paramNames, const Vector<String>& paramValues) = 0;
+        virtual PassRefPtrWillBeRawPtr<Widget> createJavaAppletWidget(HTMLAppletElement*, const KURL& baseURL, const Vector<String>& paramNames, const Vector<String>& paramValues) = 0;
 
         virtual ObjectContentType objectContentType(const KURL&, const String& mimeType, bool shouldPreferPlugInsForImages) = 0;