[Chromium] Do not recompute viewport on same page navigation

[Chromium] Do not recompute viewport on same page navigation
https://bugs.webkit.org/show_bug.cgi?id=75576

Reviewed by Darin Fisher.

Added parameter isNavigationWithinPage to WebViewImpl::didCommitLoad
that indicates whether a same-page navigation has just occurred.

The page scale factor flag is reset only on navigation to a new page.
If the flag is not set, viewport and page scale will be recomputed on
layoutUpdated.

* src/FrameLoaderClientImpl.cpp:
(WebKit::FrameLoaderClientImpl::dispatchDidNavigateWithinPage):
(WebKit::FrameLoaderClientImpl::dispatchDidCommitLoad):
* src/WebViewImpl.cpp:
(WebKit::WebViewImpl::didCommitLoad):
(WebKit::WebViewImpl::observeNewNavigation):
* src/WebViewImpl.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@105528 268f45cc-cd09-0410-ab3c-d52691b4dbfc