Bug 764299 (Part 1) - Add hashing to SVGImageContext. r=dholbert
Bug 764299 (Part 2) - Add a temporary surface cache to imagelib. r=dholbert
Bug 764299 (Part 3) - Add memory reporting to the surface cache. r=njn
Bug 764299 (Part 4) - Cache rasterized surfaces in VectorImage. r=dholbert