Merge 90599 - Work around Skia PDF's lack of inverted path support.

Merge 90599 - Work around Skia PDF's lack of inverted path support.
https://bugs.webkit.org/show_bug.cgi?id=64032

Patch by Steve VanDeBogart <vandebo@chromium.org>; on 2011-07-07
Reviewed by James Robinson.

The trick used in http://neugierig.org/software/chromium/notes/2010/07/clipping.html
to support antialiased clips doesn't work when printing to Skia's PDF backend because
the backend does not support inverted paths. This manifests as rounded buttons not being
drawn when printing, tracked as Chrome bug 79519.

However, when the output is a vector device, like PDF, we don't need antialiased clips.
It's up to the PDF rendering engine to do that.  So we can simply disable the antialiased
clip code if the output is a vector device.

I think the fix isn't testable because it requires examining the printed output.

* platform/graphics/skia/PlatformContextSkia.cpp:
(WebCore::PlatformContextSkia::clipPathAntiAliased):

TBR=vandebo@chromium.org
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=91207