Replace Backend with JavaScriptBackend.

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, CodegenWorkItem;
 import '../common/names.dart';
@@ skipping 796 matching lines @@
       // TODO(sra): The element type of a container type mask might be better.
       TypeMask type = astAdapter.inferredIndexType(forInStatement);
 
       HInstruction index = localsHandler.readLocal(indexVariable);
       HInstruction value = new HIndex(array, index, null, type);
       add(value);
 
       Local loopVariableLocal = astAdapter.getLocal(forInStatement.variable);
       localsHandler.updateLocal(loopVariableLocal, value);
       // Hint to name loop value after name of loop variable.
-      if (loopVariableLocal is !SyntheticLocal) {
+      if (loopVariableLocal is! SyntheticLocal) {
         value.sourceElement ??= loopVariableLocal;
       }
 
       forInStatement.body.accept(this);
     }
 
     void buildUpdate() {
       // See buildBody as to why we check here.
       buildConcurrentModificationErrorCheck();
 
@@ skipping 41 matching lines @@
     }
 
     void buildBody() {
       TypeMask mask = astAdapter.typeOfIteratorCurrent(forInStatement);
       _pushDynamicInvocation(forInStatement, mask, [iterator],
           selector: Selectors.current);
       Local loopVariableLocal = astAdapter.getLocal(forInStatement.variable);
       HInstruction value = pop();
       localsHandler.updateLocal(loopVariableLocal, value);
       // Hint to name loop value after name of loop variable.
-      if (loopVariableLocal is !SyntheticLocal) {
+      if (loopVariableLocal is! SyntheticLocal) {
         value.sourceElement ??= loopVariableLocal;
       }
       forInStatement.body.accept(this);
     }
 
     loopHandler.handleLoop(
         forInStatement, buildInitializer, buildCondition, () {}, buildBody);
   }
 
   void _buildAsyncForIn(ir.ForInStatement forInStatement) {
@@ skipping 2331 matching lines @@
     enterBlock.setBlockFlow(
         new HTryBlockInformation(
             kernelBuilder.wrapStatementGraph(bodyGraph),
             exception,
             kernelBuilder.wrapStatementGraph(catchGraph),
             kernelBuilder.wrapStatementGraph(finallyGraph)),
         exitBlock);
     kernelBuilder.inTryStatement = previouslyInTryStatement;
   }
 }