Check function type equivalence

tests/compiler/dart2js/equivalence/check_functions.dart

 // Copyright (c) 2017, 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.
 
 /// Equivalence test functions for data objects.
 
 library dart2js.equivalence.functions;
 
 import 'package:expect/expect.dart';
 import 'package:compiler/src/common/resolution.dart';
@@ skipping 451 matching lines @@
         env2.isDeferredLoadLibraryGetter(member2));
 
     checkListEquivalence(
         member1,
         member2,
         'metadata',
         env1.getMemberMetadata(member1),
         env2.getMemberMetadata(member2),
         strategy.testConstantValues);
 
-    // TODO(johnniwinther): Check function type. Currently hitting problems with
-    // return types of generative constructors, function types referring to
-    // typedefs and forwarding constructors.
-    /*if (member1 is FunctionEntity && member2 is FunctionEntity) {
+    if (member1 is FunctionEntity && member2 is FunctionEntity) {
       check(member1, member2, 'getFunctionType', env1.getFunctionType(member1),
           env2.getFunctionType(member2), strategy.typeEquivalence);
-    }*/
+    }
   }
 
   checkSetEquivalence(env1, env2, 'libraries', env1.libraries, env2.libraries,
       strategy.elementEquivalence,
       onSameElement: (LibraryEntity lib1, LibraryEntity lib2) {
     Expect.identical(lib1, env1.lookupLibrary(lib1.canonicalUri));
     Expect.identical(lib2, env2.lookupLibrary(lib2.canonicalUri));
 
     // TODO(johnniwinther): Check libraryName.
 
@@ skipping 686 matching lines @@
         print('  ${js.nodeToString(node1)}');
         print('  ${js.nodeToString(node2)}');
       }
       return expectedValue == label2;
     } else {
       labelsMap[label1] = label2;
       return true;
     }
   }
 }