Fix x4121 warnings

- Fix warning X4121: gradient-based operations must be moved out of flow
  control to prevent divergence. Performance may improve by using a non-gradient operation
- This is seen in Firefox Stable (34) on Windows
- This fix seems to give small amount of fps boost

Aspirin model file updated

Conflicts:
	src/math/Ray.js

Conflicts:
	examples/webgl_decals.html

Updated the Aspirin PDB file to be chemically accurate, Fixes #5779.