Subpixel rendering: Selection gap produces a pixel line overlap on inline boxes.
https://bugs.webkit.org/show_bug.cgi?id=133429

Reviewed by Simon Fraser.

Do not floor logical right/left values when selection gap is calculated for RenderBlocks.
It produces overlapping line/gap because the floored value is intersecting/too far from the
non-floored content selection rect.

Source/WebCore:
Tests: fast/inline/hidpi-selection-gap-and-inline-selection-have-gap-rtl.html
       fast/inline/hidpi-selection-gap-overlaps-inline-selection.html

* rendering/RenderBlock.cpp:
(WebCore::RenderBlock::logicalLeftSelectionGap):
(WebCore::RenderBlock::logicalRightSelectionGap):

LayoutTests:
* platform/mac/TestExpectations: add ML failure due to font sizing. (Ahem can't be used here)
* fast/inline/hidpi-selection-gap-and-inline-selection-have-gap-rtl-expected.html: Added.
* fast/inline/hidpi-selection-gap-and-inline-selection-have-gap-rtl.html: Added.
* fast/inline/hidpi-selection-gap-overlaps-inline-selection-expected.html: Added.
* fast/inline/hidpi-selection-gap-overlaps-inline-selection.html: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@169515 268f45cc-cd09-0410-ab3c-d52691b4dbfc