Remove instance and shadow tree debugging

Remove instance and shadow tree debugging, since instance tree will be removed and for the shadow tree
we can use Inspector. Also note that this code (once enabled) started to fail to compile at some point.

BUG=313438
NOTRY=true

Review URL: https://codereview.chromium.org/262413002

git-svn-id: svn://svn.chromium.org/blink/trunk@173404 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Oilpan: trace pointers in HTMLMeterElement and get rid of RefPtrs.

R=zerny@chromium.org,haraken@chromium.org

Review URL: https://codereview.chromium.org/270103003

git-svn-id: svn://svn.chromium.org/blink/trunk@173405 bbb929c8-8fbe-4397-9dbb-9b2b20218538