Reviewed by Simon Hausmann and Kenneth Rohde Christiansen.

        [Qt] Refactor shadow state handling in GraphicsContextQt
        https://bugs.webkit.org/show_bug.cgi?id=44006

        * platform/graphics/qt/GraphicsContextQt.cpp:
        (WebCore::GraphicsContextPlatformPrivate::): Added shadow states as
        member variables.
        (WebCore::GraphicsContextPlatformPrivate::hasShadow): Convenient
        function to check whether there is shadow or not.
        (WebCore::GraphicsContextPlatformPrivate::GraphicsContextPlatformPrivate):
        (WebCore::GraphicsContext::drawRect): Use shadow states instead of
        calling getShadow.
        (WebCore::GraphicsContext::drawLine): ditto.
        (WebCore::GraphicsContext::strokeArc): ditto.
        (WebCore::GraphicsContext::drawConvexPolygon): ditto.
        (WebCore::GraphicsContext::fillPath): ditto.
        (WebCore::GraphicsContext::strokePath): ditto.
        (WebCore::GraphicsContext::fillRect): Removes the use of helper function
        drawBorderlessRectShadow as the code already becomes a lot simpler.
        (WebCore::GraphicsContext::fillRoundedRect): Removes the use of helper
		function drawFilledShadowPath as the code already becomes a lot simpler.
        (WebCore::GraphicsContext::setPlatformShadow): Store shadow states
        and find out the shadow type (complexity) for future use.
        (WebCore::GraphicsContext::clearPlatformShadow): Reset shadow states.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@65362 268f45cc-cd09-0410-ab3c-d52691b4dbfc