The hashed query performs significantly faster than std::map.
This improves performance in applications which use Bind* often.

Also use the same scheme for the Context-managed resources.

BUG=angleproject:1333

Change-Id: I8a1f25d80e060c62dab1f86005e1bc4df1c06dba
Reviewed-on: https://chromium-review.googlesource.com/331387Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>