Scrollbar corner can be drawn outside containing frame
https://bugs.webkit.org/show_bug.cgi?id=133131
<rdar://problem/16382769>

Reviewed by Simon Fraser.

Source/WebCore:

Merged from Blink (patch by Levi Weintraub):
<https://src.chromium.org/viewvc/blink?revision=170625&view=revision>

Fixes an issue where the scroll corner may be painted outside the rectangle of
its associated frame by setting a clip rectangle before painting the scroll bar(s)
and scroll corner.

Test: scrollbars/custom-scrollbars-paint-outside-iframe.html

* platform/ScrollView.cpp:
(WebCore::ScrollView::paint):

LayoutTests:

Add DRT test that was derived from the test included in
<https://src.chromium.org/viewvc/blink?revision=170625&view=revision>.

* scrollbars/custom-scrollbars-paint-outside-iframe-expected.html: Added.
* scrollbars/custom-scrollbars-paint-outside-iframe.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@173046 268f45cc-cd09-0410-ab3c-d52691b4dbfc
5 files changed