Oilpan: Further relax worker emptiness assert and make it a debug only assert.

The release assert is firing in Chrome 36 and 37. We know that the
assert is currently flaky because of conservative stack scanning
and long chains of RefPtrs/Persistents.

R=erik.corry@gmail.com, haraken@chromium.org, oilpan-reviews@chromium.org
BUG=379745

Review URL: https://codereview.chromium.org/316443003

git-svn-id: svn://svn.chromium.org/blink/trunk@175354 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: use new header to distinguish "DevTools" requests.

BUG=245436

Review URL: https://codereview.chromium.org/315543002

git-svn-id: svn://svn.chromium.org/blink/trunk@175355 bbb929c8-8fbe-4397-9dbb-9b2b20218538