Auto merge of #1533 - JerryShih:export-texture-max-size, r=glennw
Auto merge of #1533 - JerryShih:export-texture-max-size, r=glennw

Export max texture size in renderer.

There are some assert for the texture size checking.
https://hg.mozilla.org/mozilla-central/annotate/7ce557b85b61/gfx/webrender/src/texture_cache.rs#l693

I'm going to export the max texture size and handle the size problem in user space.

servo/webrender,servo/webrender,servo/webrender,servo/webrender,servo/webrender,servo/webrender