Clean up the way layout tests force elements to opt in/out of composited scrolling.

Source/core/testing/Internals.h

Index: Source/core/testing/Internals.h
diff --git a/Source/core/testing/Internals.h b/Source/core/testing/Internals.h
index 4540909f51c68123632fa0a38a12986db46fccd6..d13e164bae623ca8b5c02c7797f070b38b28b844 100644
--- a/Source/core/testing/Internals.h
+++ b/Source/core/testing/Internals.h
@@ -221,8 +221,17 @@ public:
     String layerTreeAsText(Document*, unsigned flags, ExceptionCode&) const;
     String layerTreeAsText(Document*, ExceptionCode&) const;
 
-    PassRefPtr<NodeList> paintOrderListBeforePromote(Element* element, ExceptionCode& ec);
-    PassRefPtr<NodeList> paintOrderListAfterPromote(Element* element, ExceptionCode& ec);
+    PassRefPtr<NodeList> paintOrderListBeforePromote(Element*, ExceptionCode&);
+    PassRefPtr<NodeList> paintOrderListAfterPromote(Element*, ExceptionCode&);
+
+    enum {
+        // Values need to be kept in sync with Internals.idl.
+        DoNotForceCompositedScrolling = 0,
+        ForceCompositedScrollingOn = 1,
+        ForceCompositedScrollingOff = 2
+    };

[Julien - ping for review, 2013/05/06 22:56:59]

I don't think we need this enum as you don't poke into the |unsigned| returned
from JavaScript.

[Ian Vollick, 2013/05/08 13:10:58]

I didn't think so either, but it seems to be used when setting up the v8
bindings. It looks like it tries to find some c++ entity with the same name as
the constants in the .idl file to bind to.

+
+    void setNeedsCompositedScrolling(Element*, unsigned value, ExceptionCode&);
 
     String repaintRectsAsText(Document*, ExceptionCode&) const;
     String scrollingStateTreeAsText(Document*, ExceptionCode&) const;