Overflow can be cleared just before it is computed
https://bugs.webkit.org/show_bug.cgi?id=110361

Reviewed by David Hyatt.

Overflow can be cleared just before it is computed in a lot of places because overflow computation happens all at once
now rather than cumulatively during layout. Any object that doesn't use computeOverflow() will still need to clear it manually
though.

No new tests, refactoring.

* rendering/RenderBlock.cpp:
(WebCore::RenderBlock::layoutBlock):
(WebCore::RenderBlock::computeOverflow):
(WebCore::RenderBlock::simplifiedLayout):
* rendering/RenderBlockLineLayout.cpp:
(WebCore::RenderBlock::layoutInlineChildren):
* rendering/RenderDeprecatedFlexibleBox.cpp:
(WebCore::RenderDeprecatedFlexibleBox::layoutBlock):
* rendering/RenderFlexibleBox.cpp:
(WebCore::RenderFlexibleBox::layoutBlock):
* rendering/RenderGrid.cpp:
(WebCore::RenderGrid::layoutBlock):
* rendering/RenderRubyRun.cpp:
(WebCore::RenderRubyRun::layout):
* rendering/RenderTable.cpp:
(WebCore::RenderTable::layout):
* rendering/RenderTextControlSingleLine.cpp:
(WebCore::RenderTextControlSingleLine::layout):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@143627 268f45cc-cd09-0410-ab3c-d52691b4dbfc