[css-typed-om] Don't use mutable property value set unnecessarily.

We currently call EnsureMutableInlineStyle() when calling styleMap.get,
even though we don't need it to be mutable. EnsureMutableInlineStyle()
also has some overhead of copy-on-write. This patch just calls
InlineStyle() instead, which should be slightly faster as well.

Bug: 808933
Change-Id: I3f0db400b896a0be3888e61bdd8dd80783f7225c
Reviewed-on: https://chromium-review.googlesource.com/910168
Reviewed-by: nainar <nainar@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#535630}
1 file changed