🥕 Use ToPixelSnappedRect when painting CaretDisplayItemClient.

Despite getting the exact input bounds in the DCHECK statements of the
linked bug, I'm unable to reproduce this failure locally. I tried
adding margin-top and margin-left to the
drag-far-outside-multicol-crash.html test case, but even when they
matched up with those reported, the DCHECK wasn't triggered.

Other uses of DrawingRecorder use ToPixelSnappedRect, so hopefully
changing the CaretDisplayItemClient logic to use it too may fix the
issue in the wild.

This CL doesn't remove the extra logging added to the DCHECK, in case
this change doesn't actually fix it.

Bug: 1441243
Change-Id: Ic55947a568d33a1f6c331294010c332002e9180c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4546188


Auto-Submit: Peter Conn <peconn@chromium.org>
Commit-Queue: Philip Rogers <pdr@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1146749}