Fix GC pauses by reusing canvas elements
* Replace the 'scan' function, which maps a WebGL object to an
  associated integer id, with a 'name' property stored on the object.
  The linear scan was rather slow, and as the vector grew in size
  games were slowing to a few fps.
glGenTextures: correct the setting of the object name.
Document canvasPool
Add missing braces
Merge pull request #1354 from fhd/fix-gc-pauses

Fix GC pauses by reusing canvas elements
Merge pull request #1362 from dtc/obj-name

Replace the 'scan' function, which maps a WebGL object to anassociated integer id, with a 'name' property stored on the object. The linear scan was rather slow, and as the vector grew in size  games were slowing to a few fps.