[EFL][WK2] Build break after r149004
https://bugs.webkit.org/show_bug.cgi?id=115066

Reviewed by Tim Horton.

* WebProcess/WebPage/CoordinatedGraphics/CoordinatedLayerTreeHost.cpp:
(WebKit::CoordinatedLayerTreeHost::pageBackgroundTransparencyChanged):
Added dummy method for new virtual method.
* WebProcess/WebPage/CoordinatedGraphics/CoordinatedLayerTreeHost.h:
(CoordinatedLayerTreeHost): Ditto.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149008 268f45cc-cd09-0410-ab3c-d52691b4dbfc