Add binding test case of HTMLHRElement and HTMLParagraphElement.
auto merge of #691 : june0cho/servo/genBinding_Body, r=jdm

I commented out the last line of HTMLBodyElement.webidl, 'HTMLBodyElement implements WindowEventHandlers;' in order to avoid compile error.
auto merge of #693 : saneyuki/servo/fix, r=jdm

I forgot to add testcases.
Generate HTMLIFrameElement bindings.
auto merge of #686 : jdm/servo/nodesnodesnodes, r=jack
Generate bindings for HTMLBRElement