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 doesn't work with 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.
Created attachment 142802 [details] Patch
Comment on attachment 142802 [details] Patch OK.
Comment on attachment 142802 [details] Patch Clearing flags on attachment: 142802 Committed r117659: <http://trac.webkit.org/changeset/117659>
All reviewed patches have been landed. Closing bug.