Save transform context for filters

Otherwise we get weird behavior on filters while transforming.

TBR=

Bug: 901759
Change-Id: I1d487f500024a309bdb4002ba19a20387b3bb251
Reviewed-on: https://chromium-review.googlesource.com/c/1329342Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Commit-Queue: Fernando Serboncini <fserb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606861}

third_party/blink/renderer/modules/canvas/canvas2d/base_rendering_context_2d.h

@@ -488,6 +488,7 @@ void BaseRenderingContext2D::CompositedDraw(
     PaintFlags shadow_flags =
         *GetState().GetFlags(paint_type, kDrawShadowOnly, image_type);
     int save_count = c->getSaveCount();
+    c->save();
     if (filter) {
       PaintFlags foreground_flags =
           *GetState().GetFlags(paint_type, kDrawForegroundOnly, image_type);