Bug 998869 part 1 - build fontlist more lazily (non-linux). r=jfkthame
Bug 998869 part 2 - switch to GetFontAt(0) to GetFirstValidFont(). r=jfkthame
Bug 998869 part 3 - rename userfont class methods. r=heycam
Bug 998869 part 4 - rename fontgroup methods. r=heycam
Bug 998869 part 5 - lazily load userfonts (non-linux). r=jfkthame