Bug 1020865 - Implement the dialog displayed upon form.requestAutocomplete(). r=MattN

--HG--
rename : toolkit/components/formautofill/test/chrome/test_requestAutocomplete_disabled.html => toolkit/components/formautofill/test/chrome/test_requestAutocomplete_cancel.html
Bug 1020602 - Send serialized elements to requestAutocomplete UI. r=MattN
Bug 1020607 - Populate pending elements with values given by requestAutocomplete UI. r=MattN