anchor.diff:          return getExtensionSymbolInternal(firstArg.value);
         }
       }
  -    if (target == coreTypes.identicalProcedure) {
  +    if (target == _coreTypes.identicalProcedure) {
         return _emitCoreIdenticalCall(node.arguments.positional);
       }
       if (_isDebuggerCall(target)) {
  
positive.code:             [className, runtimeModule, className]));
          return null;
        }
        if (c == coreTypes.boolClass) {
          body.add(js.statement(
              '#.is = function is_bool(o) { return o === true || o === false; }',
              className));
  
negative.code:       var labelState = js_ast.TemporaryId("labelState");
        // TODO(markzipan): Retrieve the real label name with source offsets
        var labelName = 'SL${_switchLabelStates.length}';
        _switchLabelStates[node] = _SwitchLabelState(labelName, labelState);
  
        for (var c in node.cases) {
          var subcases =
  