docs: private void addSwitchCase(Node switchBlock, Node caseExpression,
                                 Node statements)
      {
          if (switchBlock.getType() != Token.BLOCK) throw Kit.codeBug();
          Jump switchNode = (Jump)switchBlock.getFirstChild();
          if (switchNode.getType() != Token.SWITCH) throw Kit.codeBug();
  
          Node gotoTarget = Node.newTarget();
          if (caseExpression != null) {
              Jump caseNode = new Jump(Token.CASE, caseExpression);
              caseNode.target = gotoTarget;
              switchNode.addChildToBack(caseNode);
          } else {
              switchNode.setDefault(gotoTarget);
          }
          switchBlock.addChildToBack(gotoTarget);
          switchBlock.addChildToBack(statements);
      }