anchor.diff:    void transformExpressions(List<Expression> nodes, TreeNode parent) {
       constantEvaluator.withNewEnvironment(() {
         for (int i = 0; i < nodes.length; ++i) {
  -        nodes[i] = tryEvaluateAndTransformWithContext(parent, nodes[i])
  +        nodes[i] = evaluateAndTransformWithContext(parent, nodes[i])
             ..parent = parent;
         }
       });
  
positive.code:         transformAnnotations(node.annotations, node);
          if (node.initializer != null) {
            node.initializer =
                tryEvaluateAndTransformWithContext(node, node.initializer)
                  ..parent = node;
          }
        } else {
  
negative.code:       transformAnnotations(variable.annotations, variable);
        if (variable.initializer != null) {
          variable.initializer =
              evaluateAndTransformWithContext(variable, variable.initializer)
                ..parent = variable;
        }
      }
  