Move platform/wtf/allocator.{h.cc} to platform/wtf/allocator/

This CL moves platform/wtf/allocator.{h.cc} to platform/wtf/allocator/
and ports other dependent files to refer to a new include path.

Bug: 950130
Change-Id: If4f4941083786606fe3312dd71c317453019bddc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1558550
Commit-Queue: Abhijeet Kandalkar <abhijeet@igalia.com>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#669129}
1115 files changed