anchor.diff:      push(expression ?? NullValue.Expression);
     }
   
  +  @override
     void endForIn(
         Token awaitToken, Token forToken, Token inKeyword, Token endToken) {
       debugEvent("ForIn");
  
positive.code:     }
    }
  
    void endExpressionStatement(Token token) {
      debugEvent("ExpressionStatement");
      push(new ExpressionStatement(popForEffect()));
    }
  
    void endArguments(int count, Token beginToken, Token endToken) {
      debugEvent("Arguments");
      List arguments = popList(count) ?? <Expression>[];
  
negative.code:     exitLoopOrSwitch(result);
    }
  
    @override
    void handleCaseMatch(Token caseKeyword, Token colon) {
      debugEvent("CaseMatch");
      // Do nothing. Handled by [handleSwitchCase].
    }
  
    @override
    void handleBreakStatement(
        bool hasTarget, Token breakKeyword, Token endToken) {
      debugEvent("BreakStatement");
  