New MainFrame views should inherit fixed layout settings from existing MainFrame...

New MainFrame views should inherit fixed layout settings from existing MainFrame view in Chromium.
https://bugs.webkit.org/show_bug.cgi?id=66780

Fixed layout mode is set from WebViewImpl, but new main FrameViews are created on loading new pages. The new page's FrameView should get its
fixed layout settings from the current page.

Reviewed by Darin Fisher.

* src/WebFrameImpl.cpp:
(WebKit::WebFrameImpl::createFrameView):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@93622 268f45cc-cd09-0410-ab3c-d52691b4dbfc