Restore emmet.io support

close FreeCodeCamp/FreeCodeCamp#2720

client/commonFramework.js

@@ -216,6 +216,14 @@ var allSeeds = '';
     });
 })();
 
+var defaultKeymap = {
+  'Cmd-E': 'emmet.expand_abbreviation',
+  'Tab': 'emmet.expand_abbreviation_with_tab',
+  'Enter': 'emmet.insert_formatted_line_break_only'
+};
+
+emmetCodeMirror(editor, defaultKeymap);
+
 editor.setOption('extraKeys', {
   Tab: function(cm) {
     if (cm.somethingSelected()) {