Clean up unnecessary headers of std containers

Including unnecessary headers of std containers might have
been left as garbage after replacing std containers with
WTF equivalent, so this CL cleans up unnecessary headers,
<map> and <vector>, of std containers.

Bug: 952716
Change-Id: I106cc029ca57d476b32de64f394a5216221a4e83
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1703157
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Miyoung Shin <myid.shin@igalia.com>
Cr-Commit-Position: refs/heads/master@{#678142}