Remove js.Sequence and use binary comma operator instead.

sdk/lib/_internal/compiler/implementation/js/template.dart

 // Copyright (c) 2014, 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.
 
 part of js;
 
 class TemplateManager {
   Map<String, Template> expressionTemplates = new Map<String, Template>();
   Map<String, Template> statementTemplates = new Map<String, Template>();
 
@@ skipping 436 matching lines @@
     return (arguments) {
       List<VariableInitialization> declarations = <VariableInitialization>[];
       for (Instantiator instantiator in declarationMakers) {
         var result = instantiator(arguments);
         declarations.add(result);
       }
       return new VariableDeclarationList(declarations);
     };
   }
 
-  Instantiator visitSequence(Sequence node) => TODO('visitSequence');
-
   Instantiator visitAssignment(Assignment node) {
     Instantiator makeLeftHandSide = visit(node.leftHandSide);
     String op = node.op;
     Instantiator makeValue = visitNullable(node.value);
     return (arguments) {
       return new Assignment.compound(
           makeLeftHandSide(arguments),
           op,
           makeValue(arguments));
     };
@@ skipping 198 matching lines @@
     if (count != before) containsInterpolatedNode.add(node);
     return null;
   }
 
   visitInterpolatedNode(InterpolatedNode node) {
     interpolatedNodes.add(node);
     containsInterpolatedNode.add(node);
     ++count;
   }
 }