Extract SuperMemberData from JavaScriptBackend

tests/compiler/dart2js/inference/inference_test_helper.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.
 
 import 'package:compiler/src/common.dart';
 import 'package:compiler/src/common_elements.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/elements/elements.dart';
 import 'package:compiler/src/elements/entities.dart';
 import 'package:compiler/src/resolution/tree_elements.dart';
@@ skipping 30 matching lines @@
     } else {
       checkMember(compiler, expectedMap, member);
     }
   });
   expectedMap.forEach((Id id, String expected) {
     reportHere(
         compiler.reporter,
         computeSpannable(compiler.elementEnvironment, mainUri, id),
         'expected:${expected},actual:null');
   });
-  Expect.isTrue(expectedMap.isEmpty,
-      "Ids not found: $expectedMap.");
+  Expect.isTrue(expectedMap.isEmpty, "Ids not found: $expectedMap.");
 }
 
 void checkMemberAstTypeMasks(
     Compiler compiler, Map<Id, String> expectedMap, MemberElement member) {
   ResolvedAst resolvedAst = member.resolvedAst;
   if (resolvedAst.kind != ResolvedAstKind.PARSED) return;
   compiler.reporter.withCurrentElement(member.implementation, () {
     new TypeMaskChecker(compiler.reporter, expectedMap, resolvedAst,
             compiler.globalInference.results)
         .check();
@@ skipping 109 matching lines @@
   visitSend(Send node) {
     checkSend(node);
     visitNode(node);
   }
 
   visitSendSet(SendSet node) {
     checkSend(node);
     visitNode(node);
   }
 }