1) We use BuiltInResources to pass the hash function to 
   ANGLE, deciding whether we applies hash function or not.
2) We use 64 bits hashing function, because 64 bits is 16
   bytes using hex representation, plus the "webgl_" prefix,
   we can keep the names under 128 (WebGL allows 5 levels of
   nesting in structures).  If chooseing 128 bits, we will
   go beyond 128 characters, and some drivers can't handle
   that safely.

ANGLEBUG=315
Review URL: https://codereview.appspot.com/6822077

git-svn-id: https://angleproject.googlecode.com/svn/trunk@1384 736b8ea6-26fd-11df-bfd4-992fa37f6226