Subpixel rendering: ebay.com rotating billboard on the main page has cut off buttons.
https://bugs.webkit.org/show_bug.cgi?id=134636
<rdar://problem/17529112>

Reviewed by Darin Adler.

Missing pixel snapping when clipping the transparency layer for BackgroundBleedUseTransparencyLayer.
Clipping needs to take the same snapping strategy as the rest of the painting code.

Source/WebCore:
Test: fast/borders/border-radius-on-subpixel-position-non-hidpi.html

* rendering/RenderBox.cpp:
(WebCore::RenderBox::paintBoxDecorations):

LayoutTests:
* fast/borders/border-radius-on-subpixel-position-non-hidpi-expected.html: Added.
* fast/borders/border-radius-on-subpixel-position-non-hidpi.html: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@170817 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Fast path for jsStringWithCache() when asked for the same string repeatedly.
<https://webkit.org/b/134635>

Source/JavaScriptCore:
Also moved the whole thing from WebCore to JavaScriptCore since it
makes more sense here, and inline the lightweight checks, leaving only
the hashmap stuff out of line.

Reviewed by Darin Adler.

* runtime/JSString.cpp:
(JSC::jsStringWithCacheSlowCase):
* runtime/JSString.h:
(JSC::jsStringWithCache):
* runtime/VM.h:

Source/WebCore:
Reviewed by Darin Adler.

* WebCore.exp.in:
* bindings/js/JSDOMBinding.cpp:
(WebCore::jsStringWithCache): Deleted.
* bindings/js/JSDOMBinding.h:
(WebCore::JSValueTraits<String>::arrayJSValue):
(WebCore::jsStringWithCache): Deleted.
* bridge/c/c_utility.cpp:
(JSC::Bindings::convertNPVariantToValue):
* loader/cache/CachedResourceHandle.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@170818 268f45cc-cd09-0410-ab3c-d52691b4dbfc