[LayoutNG] Remove NGPaintFragment::SelfInkOverflow

Following CL:1510613, NGPaintFragment::SelfInkOverflow
returns InkOverflow which contains ContentInkOverflow. There
are several callers that seem to assume it's for self-only
because the function name has "Self".

This patch removes the function and let callers call the
appropriate functions in NGPhysicalFragment.

This is part of paint performance efforts as SSM indicates
computing InkOverflow is consuming more time in NG.

Bug: 936024
Change-Id: I6985cb9a1a1509c02a46c115af6fd38a216d85d4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1510692
Commit-Queue: Koji Ishii <kojii@chromium.org>
Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#639035}
4 files changed