Strong mode cleaning of many dart2js tests.

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 606 matching lines @@
   InterfaceType type2 = instance2.type;
   return typeEquivalence(type1, type2) &&
       instance1.kind == instance2.kind &&
       instance1.isRedirection == instance2.isRedirection;
 }
 
 bool areAbstractUsagesEquivalent(AbstractUsage usage1, AbstractUsage usage2) {
   return usage1.hasSameUsage(usage2);
 }
 
+bool _areEntitiesEquivalent(a, b) => areElementsEquivalent(a, b);
+
 void checkResolutionEnqueuers(
     BackendUsage backendUsage1,
     BackendUsage backendUsage2,
     ResolutionEnqueuer enqueuer1,
     ResolutionEnqueuer enqueuer2,
-    {bool elementEquivalence(Entity a, Entity b): areElementsEquivalent,
+    {bool elementEquivalence(Entity a, Entity b): _areEntitiesEquivalent,
     bool typeEquivalence(DartType a, DartType b): areTypesEquivalent,
     bool elementFilter(Element element),
     bool verbose: false,
     bool skipClassUsageTesting: false}) {
   elementFilter ??= (_) => true;
 
   ResolutionWorldBuilderBase worldBuilder1 = enqueuer1.worldBuilder;
   ResolutionWorldBuilderBase worldBuilder2 = enqueuer2.worldBuilder;
 
   checkSets(worldBuilder1.instantiatedTypes, worldBuilder2.instantiatedTypes,
@@ skipping 70 matching lines @@
       "JavaScriptBackend.hasFunctionApplySupport mismatch");
   Expect.equals(
       backendUsage1.isRuntimeTypeUsed,
       backendUsage2.isRuntimeTypeUsed,
       "JavaScriptBackend.hasRuntimeTypeSupport mismatch");
   Expect.equals(backendUsage1.isIsolateInUse, backendUsage2.isIsolateInUse,
       "JavaScriptBackend.hasIsolateSupport mismatch");
 }
 
 void checkCodegenEnqueuers(CodegenEnqueuer enqueuer1, CodegenEnqueuer enqueuer2,
-    {bool elementEquivalence(Entity a, Entity b): areElementsEquivalent,
+    {bool elementEquivalence(Entity a, Entity b): _areEntitiesEquivalent,
     bool typeEquivalence(DartType a, DartType b): areTypesEquivalent,
     bool elementFilter(Element element),
     bool verbose: false}) {
   CodegenWorldBuilderImpl worldBuilder1 = enqueuer1.worldBuilder;
   CodegenWorldBuilderImpl worldBuilder2 = enqueuer2.worldBuilder;
 
   checkSets(worldBuilder1.instantiatedTypes, worldBuilder2.instantiatedTypes,
       "Instantiated types mismatch", typeEquivalence,
       verbose: verbose);
 
@@ skipping 53 matching lines @@
       areAbstractUsagesEquivalent,
       verbose: verbose);
   checkMaps(
       worldBuilder1.instanceMemberUsageForTesting,
       worldBuilder2.instanceMemberUsageForTesting,
       'instanceMemberUsageForTesting',
       elementEquivalence,
       areAbstractUsagesEquivalent,
       verbose: verbose);
 }