Quota: Implement new Quota Management API behind a flag

This introduces new promise-based Quota Management API[1] behind a flag.
StorageEvent and StorageWatcher are out of scope of this CL.

[1] http://www.w3.org/TR/2013/WD-quota-api-20131105/


BUG=332325
TEST=run_webkit_tests.sh storage/quota\*
TEST=run_webkit_tests.sh fast/dom/navigator-detached-no-crash.html

Review URL: https://codereview.chromium.org/137853018

git-svn-id: svn://svn.chromium.org/blink/trunk@165829 bbb929c8-8fbe-4397-9dbb-9b2b20218538