Verify AST instead of constant values.

pkg/analyzer/lib/src/summary/summarize_const_expr.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library serialization.summarize_const_expr;
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/summary/format.dart';
 
@@ skipping 150 matching lines @@
     }
   }
 
   void _serializeBinaryExpression(BinaryExpression expr) {
     serialize(expr.leftOperand);
     serialize(expr.rightOperand);
     TokenType operator = expr.operator.type;
     if (operator == TokenType.EQ_EQ) {
       operations.add(UnlinkedConstOperation.equal);
     } else if (operator == TokenType.BANG_EQ) {
-      operations.add(UnlinkedConstOperation.equal);
-      operations.add(UnlinkedConstOperation.not);
+      operations.add(UnlinkedConstOperation.notEqual);
     } else if (operator == TokenType.AMPERSAND_AMPERSAND) {
       operations.add(UnlinkedConstOperation.and);
     } else if (operator == TokenType.BAR_BAR) {
       operations.add(UnlinkedConstOperation.or);
     } else if (operator == TokenType.CARET) {
       operations.add(UnlinkedConstOperation.bitXor);
     } else if (operator == TokenType.AMPERSAND) {
       operations.add(UnlinkedConstOperation.bitAnd);
     } else if (operator == TokenType.BAR) {
       operations.add(UnlinkedConstOperation.bitOr);
@@ skipping 124 matching lines @@
  * Error that describes a problem during a constant expression serialization.
  */
 class _ConstExprSerializationError {
   final String message;
 
   _ConstExprSerializationError(this.message);
 
   @override
   String toString() => message;
 }