[browser defs] Add MutationObserver interface
[browser defs] Add MutationObserver interface

MarcelGerber/tern,fileability/tern,marijnh/tern,marijnh/tern,othree/tern,MarcelGerber/tern,othree/tern,neoclide/tern,emacsmirror/tern,ternjs/tern,marijnh/tern,neoclide/tern,othree/tern,fileability/tern,neoclide/tern,ternjs/tern,ternjs/tern,emacsmirror/tern,fileability/tern,emacsmirror/tern,MarcelGerber/tern