Fix ResourceManager create-on-bind reallocations. *re-land with build fix for Clang* We had a funny bug where the Handle Allocator would re-allocate reserved handles after the app layer creates one with Bind rather than using Gen. This affects Textures, Buffers and Renderbuffers. Fix this by using a different allocation scheme. It should still be fast on the "good" case (using Gen) and use tree lookups on the bind case. Also add some unit tests. BUG=angleproject:942 Change-Id: I63ce608fcd6a11f92e2b5421f090551934e729ed Reviewed-on: https://chromium-review.googlesource.com/261591 Tested-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>