https://bugs.webkit.org/show_bug.cgi?id=86904

Reviewed by Eric Seidel.

In r117491, we introduced a new method of alignment for the selection rect in the sub-pixel case.
It turns out there is at least one case on Mac where this leaves a gap when painting selection rects
originating in the line box tree. This patch reverts us to the float method for the line box tree,
but retains the LayoutRect snapping for gap rects.

No new tests. Covered by existing tests with sub-pixel layout enabled.

* rendering/EllipsisBox.cpp:
(WebCore::EllipsisBox::paintSelection): Re-enabling the FloatRect flavor of
alignSelectionRectToDevicePixels for the line box tree.
* rendering/InlineTextBox.cpp:
(WebCore::alignSelectionRectToDevicePixels): Moving LayoutRect flavor to RenderBlock.
(WebCore::InlineTextBox::paintSelection): Happily clearing up the bifurcation of algorithms for
sub-pixel layout.
* rendering/InlineTextBox.h: Re-enabling the FloatRect flavor of alignSelectionRectToDevicePixels
for the line box tree.
* rendering/RenderBlock.cpp:
(WebCore::alignSelectionRectToDevicePixels): Re-seating the LayoutRect version of
alignSelectionRectToDevicePixels for use with GapRects.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@117659 268f45cc-cd09-0410-ab3c-d52691b4dbfc