code: private Node renameProperty(Node propertyName) {
      checkArgument(propertyName.isString());
      if (!renameProperties) {
        return propertyName;
      }
      Node call = IR.call(
          IR.name(NodeUtil.JSC_PROPERTY_NAME_FN).srcref(propertyName),
          propertyName);
      call.srcref(propertyName);
      call.putBooleanProp(Node.FREE_CALL, true);
      call.putBooleanProp(Node.IS_CONSTANT_NAME, true);
      return call;
    }
docs: Wraps a property string in a JSCompiler_renameProperty call.
  
  <p>Should only be called in phases running before {@link RenameProperties},
  if such a pass is even used (see {@link #renameProperties}).