Use pixelSnappedLogicalHeight for TableSection layout

Use pixelSnappedLogicalHeight for TableSection layout
https://bugs.webkit.org/show_bug.cgi?id=86665

Reviewed by Eric Seidel.

We do table layout using integers to ensure we follow the spec (see
https://trac.webkit.org/wiki/LayoutUnit for details), but were previously
flooring the logical height used in layoutRows. This caused us to mis-
calculate the intrinsic padding and grow cells beyond their proper height.

No new tests. Fully covered by existing tests with sub-pixel enabled.

* rendering/RenderBox.h:
(WebCore::RenderBox::pixelSnappedLogicalHeight): Added these convenience
methods.
(WebCore::RenderBox::pixelSnappedLogicalWidth):
* rendering/RenderTableSection.cpp:
(WebCore::RenderTableSection::layoutRows):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@117388 268f45cc-cd09-0410-ab3c-d52691b4dbfc