[CTTE] RenderHTMLCanvas's element is always a HTMLCanvasElement.
<https://webkit.org/b/121272>

Reviewed by Anders Carlsson.

Add RenderHTMLCanvas::canvasElement(), hiding element().
This function also returns a reference since this renderer cannot be anonymous.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@155668 268f45cc-cd09-0410-ab3c-d52691b4dbfc
4 files changed