Bug 923341 - Part 1: Add a gfxSurfaceDrawable constructor for a DrawTarget. r=seth
Bug 923341 - Part 2: Use SVG caches on all azure backends. r=seth
Bug 923341 - Part 3: Use azure for CreateSamplingRestrictedDrawable. r=seth
Bug 923341 - Part 4: Update CachedSurface::Drawable. r=seth