Use index in J/KTypeVariable and fix remaining inequivalence

pkg/compiler/lib/src/ssa/builder_kernel.dart

 // Copyright (c) 2016, 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:kernel/ast.dart' as ir;
 
 import '../closure.dart';
 import '../common.dart';
 import '../common/codegen.dart' show CodegenRegistry;
 import '../common/names.dart';
@@ skipping 631 matching lines @@
       _addClassTypeVariablesIfNeeded(functionNode.parent);
     }
 
     // If [functionNode] is `operator==` we explicitly add a null check at the
     // beginning of the method. This is to avoid having call sites do the null
     // check.
     if (parent is ir.Procedure &&
         parent.kind == ir.ProcedureKind.Operator &&
         parent.name.name == '==') {
       FunctionEntity method = _elementMap.getMethod(parent);
-      if (!backend.operatorEqHandlesNullArgument(method)) {
+      if (!_commonElements.operatorEqHandlesNullArgument(method)) {
         handleIf(
           visitCondition: () {
             HParameterValue parameter = parameters.values.first;
             push(new HIdentity(parameter, graph.addConstantNull(closedWorld),
                 null, commonMasks.boolType));
           },
           visitThen: () {
             closeAndGotoExit(new HReturn(
                 graph.addConstantBool(false, closedWorld),
                 // TODO(redemption): Provider source information like
@@ skipping 2843 matching lines @@
     enterBlock.setBlockFlow(
         new HTryBlockInformation(
             kernelBuilder.wrapStatementGraph(bodyGraph),
             exception,
             kernelBuilder.wrapStatementGraph(catchGraph),
             kernelBuilder.wrapStatementGraph(finallyGraph)),
         exitBlock);
     kernelBuilder.inTryStatement = previouslyInTryStatement;
   }
 }