Merge 129370 - snapToSize rounds the incorrectly for negative locations

LayoutTests/platform/mac/Skipped

 #
 # Copyright (C) 2008 Apple Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions
 # are met:
 #
 # 1.  Redistributions of source code must retain the above copyright
 #     notice, this list of conditions and the following disclaimer.
 # 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 807 matching lines @@
 fast/sub-pixel/inline-block-with-margin.html
 fast/sub-pixel/inline-block-with-padding.html
 fast/sub-pixel/large-sizes.html
 fast/sub-pixel/layout-boxes-with-zoom.html
 fast/sub-pixel/position-right-aligns-with-container.html
 fast/sub-pixel/selection/selection-gaps-at-fractional-offsets.html
 fast/sub-pixel/size-of-box-with-zoom.html
 fast/sub-pixel/table-rows-no-gaps.html
 fast/sub-pixel/sub-pixel-accumulates-to-layers.html
 fast/sub-pixel/selection/selection-rect-in-sub-pixel-table.html
+fast/sub-pixel/snap-negative-location.html
 
 # No CORS support for media elements is implemented yet.
 http/tests/security/video-cross-origin-readback.html
 
 # media/audio-repaint.html sometimes fails on Lion Debug (Tests)
 # https://bugs.webkit.org/show_bug.cgi?id=84357
 media/audio-repaint.html
 
 # Requires ENABLE(MEDIA_CAPTURE)
 fast/forms/file/file-input-capture.html
@@ skipping 248 matching lines @@
 
 # WebKit1 OOP plug-ins: Exceptions aren't thrown on invoke failure.
 plugins/npruntime/invoke-failure.html
 
 # https://bugs.webkit.org/show_bug.cgi?id=93589
 # Very flaky, often failing on retry, too.
 svg/dom/SVGScriptElement/script-change-externalResourcesRequired-while-loading.svg
 
 # Unknown failures.
 http/tests/multipart/invalid-image-data-standalone.html