Unify SVG parent checks for LayoutObject construction using always the light tree parent.
This is the last cleanup spawned from [1].
I've used the light tree parent because there are a lot of other checks that are
wrong, as noted in that discussion, and updating all those and ensuring it's
correct is a fair amount of work.
This patch ensures we're consistent, and that there's only one place to change
if we want to change the isLayoutObjectNeeded check to use the flat tree.
[1]: https://codereview.chromium.org/2684833003/
Review-Url: https://codereview.chromium.org/2688343002
Cr-Commit-Position: refs/heads/master@{#449893}
5 files changed
