Hoist paint-server transform adaption out of preparePaintServer

The additional transform computed by the helper function
RenderSVGResourceContainer::computeResourceSpaceTransform by each
paint-server (that is CTM-dependent), only depends on the input to
preparePaintServer, and not the paint-server itself.
Hoist the computation into SVGRenderSupport::updateGraphicsContext.
This in turn mean that the various preparePaintServer implementations
no longer use the passed RenderStyle (previously only used for checking
for vector-effect) and RenderSVGResourceModeFlags, so remove those.
computeResourceSpaceTransform w/ associated helpers are moved to
SVGRenderSupport.

BUG=420022

Review URL: https://codereview.chromium.org/652243002

git-svn-id: svn://svn.chromium.org/blink/trunk@183746 bbb929c8-8fbe-4397-9dbb-9b2b20218538