[Squad] Load input type=image on style recalc.

That way we would not have to re-attach the layout tree inside layout
tree rebuilding when image resources finish loading immediately.

TEST=fast/forms/image/fallback-reattach-crash.html

Bug: 843520, 845167
Change-Id: I37e6121e30b8909dd5df4483f2109d5e1e02945c
Reviewed-on: https://chromium-review.googlesource.com/1072650
Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#562239}
4 files changed