Remove DCHECK(Style()) calls and use StyleRef() instead.

This patch removes the DCHECKs added in [1], and replaces them with
StyleRef() calls which already perform the DCHECK. This makes the code
look cleaner.

[1] https://chromium-review.googlesource.com/c/551116/

Bug: 628043
Change-Id: I125890524d09abb35e0e1b224b6e2518d88894cb
Reviewed-on: https://chromium-review.googlesource.com/553797
Reviewed-by: Rune Lillesveen <rune@opera.com>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#483255}
6 files changed