Remove obsolete logging functionality from RenderLayerCompositor

We are using other methods of insight into the tree, such as the
frame viewer, debuggers, and other methods of logging. This logging
code is not only un-used, but it is a maintenance burden and
adds unnecessary cognitive load to reading this code. It is cleaner
to simply remove it now!

Review URL: https://codereview.chromium.org/51633005

git-svn-id: svn://svn.chromium.org/blink/trunk@161173 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Expose <dialog> in the accessibility tree by default.

This way accessibility technology can be aware of the
dialog. Previously, the 'dialog' role was ignored by default.

The test for this patch is on Chrome side:
https://codereview.chromium.org/55763002/

BUG=264959

Review URL: https://codereview.chromium.org/54373013

git-svn-id: svn://svn.chromium.org/blink/trunk@161174 bbb929c8-8fbe-4397-9dbb-9b2b20218538