[DevTools] Remove --disable-internal-devtools-binary-protocol.

This is the minimal change. I'll simplify the code in a separate
change, and remove the test suites in a separate change.

The update to dom-getBoxModel-expected.txt is because the flag
won't have an effect any more.

Bug: 954618

Change-Id: Ib017e78c56fa19178b2d914bfcad96f9a2187596
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1575999
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Johannes Henkel <johannes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652681}
5 files changed