Reviewed by Kenneth Russell.

        [Chromium] Add gpu acceleration flags to DumpRenderTree
        https://bugs.webkit.org/show_bug.cgi?id=60168
        Adding support for command line flags
        enable-accelerated-2d-canvas an
        enable-accelerated-drawing in DumpRenderTree.

        * DumpRenderTree/chromium/DumpRenderTree.cpp:
        (main):
        * DumpRenderTree/chromium/TestShell.cpp:
        (TestShell::TestShell):
        (TestShell::resetWebSettings):
        * DumpRenderTree/chromium/TestShell.h:
        (TestShell::setLegacyAccelerated2dCanvasEnabled):
        (TestShell::setAcceleratedDrawingEnabled):
        * DumpRenderTree/chromium/WebPreferences.cpp:
        (WebPreferences::reset):
        (WebPreferences::applyTo):
        * DumpRenderTree/chromium/WebPreferences.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@85777 268f45cc-cd09-0410-ab3c-d52691b4dbfc