CanvasRenderer: Match WebGLRenderer's handling of Offset/Repeat for Spri...

...tes

The misc_ubiquity_test2.html demo looks good. A limitation, however, is that `Sprite.material.rotation` is not supported when the sprite texture is repeated -- there were not enough degrees of freedom to get the offset/repeat and rotation correct. I do not think this is a big deal, however.

In any event, this is a step in the right direction.