Use std::find_if to find style sheet by key

Instead of a for loop we use std::find_if with a lambda, which makes the
code easier to follow.

BUG=608854

Change-Id: Ib08efabfb8d0d21da4d3397b4fb27406fe096dc1
Reviewed-on: https://chromium-review.googlesource.com/923348
Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Manish Jethani <m.jethani@eyeo.com>
Cr-Commit-Position: refs/heads/master@{#537649}
1 file changed