[Qt] Support -webkit-font-smoothing
https://bugs.webkit.org/show_bug.cgi?id=106009

Reviewed by Jocelyn Turcotte.

Source/WebCore:

Set QFont antialiasing settings based on the font smoothing settings in FontDescription.

* platform/graphics/qt/FontPlatformDataQt.cpp:
(WebCore::FontPlatformData::FontPlatformData):

Source/WebKit/qt:

Export an interface so DRT can also disable font-smoothing like WTR does.

* WebCoreSupport/DumpRenderTreeSupportQt.cpp:
(DumpRenderTreeSupportQt::setShouldUseFontSmoothing):
* WebCoreSupport/DumpRenderTreeSupportQt.h:

Tools:

Set shouldUseFontSmoothing to false to match WebKitTestRunner.

* DumpRenderTree/qt/TestRunnerQt.cpp:
(TestRunnerQt::reset):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146324 268f45cc-cd09-0410-ab3c-d52691b4dbfc