GitLab

Replace the use of std::map of std container with WTF::HashMap in
image.cc/h and use FloatSize instead of std::pair as HashMap's key.

Bug: 952716
Change-Id: I8476fd4710f71469806c6118e0dcfe37602bfe30
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1599813Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Miyoung Shin <myid.shin@igalia.com>
Cr-Commit-Position: refs/heads/master@{#657666}