leak-detector: Remove InternalSettings supplement from Page

Internal settings are ScriptWrappable and thus may retain documents
depending on whether the garbage collector(s) are able to find the settings
object through the Page supplement.

Bug: 843903, 928781
Change-Id: I53458c6eb761a98ddc0e437174a233682e442586
Reviewed-on: https://chromium-review.googlesource.com/c/1456001
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629545}
4 files changed