[BlackBerry] Initial scale changes depending on the order of page navigations
https://bugs.webkit.org/show_bug.cgi?id=114448

Patch by Jacky Jiang <zhajiang@rim.com>.
Reviewed by Rob Buis.

PR: 323941
During page transitions, absoluteVisibleOverflowSize() and contentsSize()
in fixedLayoutSize() were based on the old page when we just started or
committed provisinal load. In that case, fixedLayoutSize() is very old
page dependent and can cause inconsistent behaviors. For example, if
the old page contents width is 4000, we will get DEFAULT_MAX_LAYOUT_WIDTH 1024
as the new page's fixedLayoutSize; however, we will get 768 if we
navigate to the new page directly.
To fix that, return default layout size if the page doesn't have
virtual viewport and m_loadState is Provisional.

* Api/WebPage.cpp:
(BlackBerry::WebKit::WebPagePrivate::fixedLayoutSize):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@148225 268f45cc-cd09-0410-ab3c-d52691b4dbfc