This CL introduces a new type, MapHandles, which is a STL vector of Handle<Map>.
It is now used everywhere where lists of Handle<Maps> are required, replacing
usages of V8's internal List type.

Also-By: franzih@chromium.org
BUG=v8:6333,v8:6325
LOG=N

Review-Url: https://codereview.chromium.org/2809923002
Cr-Commit-Position: refs/heads/master@{#45211}