Remove a non-implemented method.

The RenderLayer::enclosingFilterRepaintLayer method is declared but not
defined. It has moved to RenderLayerRepainter.

BUG=

Review URL: https://codereview.chromium.org/226493002

git-svn-id: svn://svn.chromium.org/blink/trunk@170901 bbb929c8-8fbe-4397-9dbb-9b2b20218538