[CSS Shapes] shape-inside rectangle layout can fail

https://bugs.webkit.org/show_bug.cgi?id=124784

Reviewed by Darin Adler.

Early subpixel rounding/flooring/ceiling can have unwanted
side effect on the final pixel value. Delay pixel
conversions as much as possible.

Existing test is changed to reflect subpixel functionality.

Source/WebCore:

* rendering/shapes/RectangleShape.cpp:
(WebCore::RectangleShape::firstIncludedIntervalLogicalTop):

LayoutTests:

* fast/shapes/shape-inside/shape-inside-subpixel-rectangle-top-expected.html:
* platform/mac/TestExpectations:
* platform/win/TestExpectations:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162559 268f45cc-cd09-0410-ab3c-d52691b4dbfc