In order to remove the vptr from CSSCanvasValue, we need to remove the inheritance from CanvasObserver. I plan to do this in the same was as CSSImportRule, by adding a proxying observer as a member variable.
Created attachment 114040 [details] Proposed patch
Comment on attachment 114040 [details] Proposed patch r=me
Committed r99555: <http://trac.webkit.org/changeset/99555>