Emit classes using ASTs

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

 // Copyright (c) 2012, 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;
 
 abstract class NodeVisitor<T> {
   T visitProgram(Program node);
 
   T visitBlock(Block node);
@@ skipping 846 matching lines @@
 
   int get precedenceLevel => PRIMARY;
 }
 
 Prefix typeOf(Expression argument) => new Prefix('typeof', argument);
 
 Binary equals(Expression left, Expression right) {
   return new Binary('==', left, right);
 }
 
-LiteralString string(String value) => new LiteralString("'$value'");
+LiteralString string(String value) => new LiteralString('"$value"');
 
 If if_(Expression condition, Node then, [Node otherwise]) {
   return (otherwise == null)
       ? new If.noElse(condition, then)
       : new If(condition, then, otherwise);
 }
 
 Return return_([Expression value]) => new Return(value);
 
 VariableUse use(String name) => new VariableUse(name);
 
 PropertyAccess fieldAccess(Expression receiver, String fieldName) {
   return new PropertyAccess.field(receiver, fieldName);
 }
 
 Block emptyBlock() => new Block.empty();
 
+Block block1(Statement statement) => new Block(<Statement>[statement]);
+
+Block block2(Statement s1, Statement s2) => new Block(<Statement>[s1, s2]);
+
 Call call(Expression target, List<Expression> arguments) {
   return new Call(target, arguments);
 }
 
 Fun fun(List<String> parameterNames, Block body) {
   return new Fun(parameterNames.map((n) => new Parameter(n)), body);
 }
 
 Assignment assign(Expression leftHandSide, Expression value) {
   return new Assignment(leftHandSide, value);
 }
 
 Expression undefined() => new Prefix('void', new LiteralNumber('0'));