Resynthesize invalid constants as unresolved identifiers.

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

 // Copyright (c) 2015, 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 summary_resynthesizer;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
@@ skipping 244 matching lines @@
   int doublePtr = 0;
   int stringPtr = 0;
   int refPtr = 0;
   final List<Expression> stack = <Expression>[];
 
   _ConstExprBuilder(this.resynthesizer, this.uc);
 
   Expression get expr => stack.single;
 
   Expression build() {
-    // TODO(scheglov) complete implementation
+    if (uc.isInvalid) {
+      return AstFactory.identifier3(r'$$invalidConstExpr$$');
+    }
     for (UnlinkedConstOperation operation in uc.operations) {
       switch (operation) {
         case UnlinkedConstOperation.pushNull:
           _push(AstFactory.nullLiteral());
           break;
         // bool
         case UnlinkedConstOperation.pushFalse:
           _push(AstFactory.booleanLiteral(false));
           break;
         case UnlinkedConstOperation.pushTrue:
@@ skipping 1658 matching lines @@
                 }
               : () => this.element;
       // TODO(paulberry): Is it a bug that we have to pass `false` for
       // isInstantiated?
       return new DeferredFunctionTypeImpl(computer, null, typeArguments, false);
     } else {
       return null;
     }
   }
 }