Hint mode: Don't be discouraged by a document's lack of a body. Closes issue #40.

--HG--
extra : rebase_source : dfdf9cf61af76aa84841ff181f42afcf318bce6d

common/content/editor.js

@@ -624,7 +624,6 @@ const Editor = Module("editor", {
         mappings.add([modes.INSERT],
             ["<Tab>"], "Expand insert mode abbreviation",
             function () {
-                util.dumpStack("\n\n\n<Tab>");
                 editor.expandAbbreviation(modes.INSERT);
                 document.commandDispatcher.advanceFocus();
             });

common/content/hints.js

@@ -263,8 +263,6 @@ const Hints = Module("hints", {
             win = this._top;
 
         let doc = win.document;
-        if (!doc.body && !doc.document)
-            return;
 
         let [offsetX, offsetY] = this._getContainerOffsets(doc);