[BlackBerry] file:/// pages don't get correct scales after several rotations and history navigations
https://bugs.webkit.org/show_bug.cgi?id=105996

Patch by Jacky Jiang <zhajiang@rim.com>.
Reviewed by George Staikos.

PR: 273541
When navigating back to the previous page on portrait mode, we were
trying to set virtual viewport after recalculation. However, we didn't
change the fixed layout size so that we still layouted the contents at
the old virtual viewport size. In this case, the old virtual viewport
was 570 * 293 which was set in landscape mode unfortunately. There
would be no chance for such kind of contents size to fit the portrait
mode screen size nicely.
This was a regression of webkit/cc31d9bad where setViewMode() was
removed as a noop. So just get setViewMode() back to apply the fixed
layout size with a little bit change as SVG document path was proved
invalid in that patch. Thanks to George for the float comparison change.
Put a FIXME as we don't have a way to save the scale precisely before
the rotation and history navigation currently.

* Api/WebPage.cpp:
(BlackBerry::WebKit::WebPagePrivate::setLoadState):
* WebCoreSupport/FrameLoaderClientBlackBerry.cpp:
(WebCore::FrameLoaderClientBlackBerry::saveViewStateToItem):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@138699 268f45cc-cd09-0410-ab3c-d52691b4dbfc