Bug 918011 part 1.  Move RootedDictionary into its own header.  r=smaug

--HG--
rename : dom/bindings/BindingUtils.h => dom/bindings/RootedDictionary.h
Bug 918011 part 2.  Preprocess some of our test WebIDL files so we can have debug-only tests.  r=khuey
Bug 918011 part 3.  Get rid of isInOwningUnion: it's equivalent to another isMember value.  r=smaug
Bug 918011 part 4.  Support dictionaries in unions.  r=smaug
Bug 920730.  Output the WebIDL .deps files in a consistent order.  r=glandium