Fix KernelEquivalence.entityEquivalence for equi-named instance/top-level members

tests/compiler/dart2js/kernel/closed_world2_test.dart

Index: tests/compiler/dart2js/kernel/closed_world2_test.dart
diff --git a/tests/compiler/dart2js/kernel/closed_world2_test.dart b/tests/compiler/dart2js/kernel/closed_world2_test.dart
index 871779d8af1d2e559dc39d3959e1cfb8edd56df8..732c76122ee828d45498dae12d71be07ffc96ca2 100644
--- a/tests/compiler/dart2js/kernel/closed_world2_test.dart
+++ b/tests/compiler/dart2js/kernel/closed_world2_test.dart
@@ -72,6 +72,7 @@ class Class2 extends Object with Mixin {
   method3() {}
 }
  
+method1() {} // Deliberately the same name as the instance member in Mixin.
 
 @NoInline()
 main() {
@@ -83,6 +84,7 @@ main() {
   new Class2().method2();
   new Class2().method3();
   null is List<int>;
+  method1(); // Both top level and instance method named 'method1' are live.
 }
 '''
 };
@@ -93,7 +95,9 @@ main(List<String> args) {
   });
 }
 
-Future mainInternal(List<String> args,
+enum ResultKind { crashes, errors, warnings, success, failure }
+
+Future<ResultKind> mainInternal(List<String> args,
     {bool skipWarnings: false, bool skipErrors: false}) async {
   Arguments arguments = new Arguments.from(args);
   Uri entryPoint;
@@ -118,13 +122,17 @@ Future mainInternal(List<String> args,
   ElementResolutionWorldBuilder.useInstantiationMap = true;
   compiler1.resolution.retainCachesForTesting = true;
   await compiler1.run(entryPoint);
+  if (collector.crashes.isNotEmpty) {
+    print('Skipping due to crashes.');
+    return ResultKind.crashes;
+  }
   if (collector.errors.isNotEmpty && skipErrors) {
     print('Skipping due to errors.');
-    return;
+    return ResultKind.errors;
   }
   if (collector.warnings.isNotEmpty && skipWarnings) {
     print('Skipping due to warnings.');
-    return;
+    return ResultKind.warnings;
   }
   Expect.isFalse(compiler1.compilationFailed);
   ResolutionEnqueuer enqueuer1 = compiler1.enqueuer.resolution;
@@ -179,6 +187,8 @@ Future mainInternal(List<String> args,
 
   checkClosedWorlds(closedWorld1, closedWorld2, equivalence.entityEquivalence,
       verbose: arguments.verbose);
+
+  return ResultKind.success;
 }
 
 List createKernelResolutionEnqueuerListener(