Blur filter causes issues when scrolling

Blur filter causes issues when scrolling
https://bugs.webkit.org/show_bug.cgi?id=89475

Reviewed by Simon Fraser.

Source/WebCore:

This patch disables the fast scrolling when there is a fixed postioned element that
has a filter applied on its parent layer. Otherwise the scroll blitting will just
copy the outsets of the blur effect.

Test: css3/filters/blur-filter-page-scroll.html

* page/FrameView.cpp:
(WebCore::FrameView::scrollContentsFastPath):

LayoutTests:

Checking that the fixed positioned element repaints correctly when there is a blur filter
applied on its parent layer.

* css3/filters/blur-filter-page-scroll.html: Added.
* platform/chromium/css3/filters/blur-filter-page-scroll-expected.png: Added.
* platform/chromium/css3/filters/blur-filter-page-scroll-expected.txt: Added.
* platform/chromium/TestExpectations: The new test needs to be checked on Windows.
* platform/mac/css3/filters/blur-filter-page-scroll-expected.png: Added.
* platform/mac/css3/filters/blur-filter-page-scroll-expected.txt: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@121348 268f45cc-cd09-0410-ab3c-d52691b4dbfc