Resynthesize invalid types as 'dynamic'.

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/ast/standard_ast_factory.dart';
@@ skipping 1230 matching lines @@
    * is returned.
    */
   DartType buildType(bool instantiateToBoundsAllowed, int numTypeArguments,
       DartType getTypeArgument(int i), List<int> implicitFunctionTypeIndices) {
     DartType result =
         (numTypeParameters == 0 && implicitFunctionTypeIndices.isEmpty)
             ? type
             : _buildType(instantiateToBoundsAllowed, numTypeArguments,
                 getTypeArgument, implicitFunctionTypeIndices);
     if (result == null) {
-      // TODO(paulberry): figure out how to handle this case (which should
-      // only occur in the event of erroneous code).
-      throw new UnimplementedError();
+      return DynamicTypeImpl.instance;
     }
     return result;
   }
 
   /**
    * If this reference refers to a type, build a [DartType].  Otherwise return
    * `null`.  If [numTypeArguments] is the same as the [numTypeParameters],
    * the type is instantiated with type arguments returned by [getTypeArgument],
    * otherwise it is instantiated with type parameter bounds (if strong mode),
    * or with `dynamic` type arguments.
@@ skipping 625 matching lines @@
   static String _getElementIdentifier(String name, ReferenceKind kind) {
     if (kind == ReferenceKind.topLevelPropertyAccessor ||
         kind == ReferenceKind.propertyAccessor) {
       if (!name.endsWith('=')) {
         return name + '?';
       }
     }
     return name;
   }
 }