Consider this calling sequence:
glBindTexture(GL_TEXTURE_2D, 3); // create-on-bind
glGenTextures(1, tex);

Before this fix, mUnallocatedList in HandleAllocator is in reverse sorted
order. It's split into (4, MAX_UINT) and (1, 3). The glGen gets tex = 4,
and handles 1 and 2 will not be allocated until it reaches MAX_UINT.
With this fix, the elements in mUnallocatedList is in sorted order
(1, 3) and (4, MAX_UINT). So tex is 1, and we can have all rest handles.

Change-Id: If408ea92f7c243791119fe386e3e0ea27954e55c
Reviewed-on: https://chromium-review.googlesource.com/273886Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Minmin Gong <mgong@microsoft.com>