[WK2][CoordinatedGraphics] Removing duplicate scale information from WebVIew.cpp
https://bugs.webkit.org/show_bug.cgi?id=126243

Reviewed by Benjamin Poulain.

The scale factor of the WebView must reflect the same information present in
WebPageProxy.
Previously, in WebView.cpp, there was a m_contentScaleFactor member, which adds
information duplication and needs to be synchronizing with pageScaleFactor in
WebPageProxy. We can avoid this by just making WebView access and set WebPageProxy's
pageScaleFactor directly.

* UIProcess/CoordinatedGraphics/WebView.cpp:
(WebKit::WebView::WebView):
(WebKit::WebView::setContentScaleFactor):
(WebKit::WebView::transformToScene):
(WebKit::WebView::visibleContentsSize):
* UIProcess/CoordinatedGraphics/WebView.h:
(WebKit::WebView::contentScaleFactor):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@161087 268f45cc-cd09-0410-ab3c-d52691b4dbfc