Strength-reduce the "scale-factor changed" condition in LayoutSVGRoot
Spend some cycles examining the difference between the old and new
local-to-border-box transforms, and only signal scale-factor changes
if that part of the transform changed.
This also means that we now detect changes scale that we previously
didn't (like [1].)
[1] paint/invalidation/svg/absolute-sized-content-with-resources.xhtml
BUG=603956,664961
Review-Url: https://codereview.chromium.org/2559123003
Cr-Commit-Position: refs/heads/master@{#437767}
4 files changed
