function toggleQuickEditAtOffset(editor, offset) {
        editor.setCursorPos(offset.line, offset.ch);

        return _testWindow.executeCommand(Commands.TOGGLE_QUICK_EDIT);
    }
Set editor cursor position to the given offset then activate an inline editor.
@param {!Editor} editor
@param {!{line:number, ch:number}} offset
@return {$.Promise} a promise that will be resolved when an inline
 editor is created or rejected when no inline editors are available.