Scale the viewport size in SVGImagePainter

LayoutImageResource::GetImage expects a zoomed container size (it passes
it unmodified to SVGImageForContainer::Create which unzooms it), so we
need to scale the viewport size before passing it.

Bug: 859774
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I24f7f0b1f402aaef112882ab146d573981889cae
Reviewed-on: https://chromium-review.googlesource.com/1124163
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#572190}
3 files changed