code: function methodNameFromTree(tree) {
    // COMPUTED_PROPERTY_NAME such as [Symbol.iterator]
    if (tree.type === COMPUTED_PROPERTY_NAME) {
      return '';
    }
  
    if (tree.literalToken && tree.literalToken.type === STRING) {
      return tree.getStringValue().substr(1, -1);
    }
  
    // identifier, delete, import, catch, etc.
    return tree.getStringValue();
  }
docs: Maximally minimal classes  http://wiki.ecmascript.org/doku.php?id=strawman:maximally_minimal_classes  This transforms class declarations and class expressions.  class C extends B { constructor(x) { super(); } method() { super.m(); } }  =>  var C = function(x) { $traceurRuntime.superConstructor($C).call(this)); }; var $C = $traceurRuntime.createClass(C, { method: function() { $traceurRuntime.superGet(this, $C.prototype, 'm').call(this); } }, {}, B);  The super property and super calls are transformed in the SuperTransformer.