NOT FOR REVIEW - Update comp-scrolling state at a well defined point in the pipeline.

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..c21c5be503dd42f1f57e33c539e5b2d3da2b5b6a 100644
--- a/Source/core/testing/Internals.h
+++ b/Source/core/testing/Internals.h
@@ -221,8 +221,16 @@ 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
+    };
+    void setNeedsCompositedScrolling(Element*, unsigned value, ExceptionCode&);
 
     String repaintRectsAsText(Document*, ExceptionCode&) const;
     String scrollingStateTreeAsText(Document*, ExceptionCode&) const;