Lower map literals to constructor or function calls in builder

pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.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.
 
 library dart2js.ir_nodes_sexpr;
 
 import '../constants/values.dart';
 import '../util/util.dart';
 import 'cps_ir_nodes.dart';
 import '../universe/call_structure.dart' show
@@ skipping 259 matching lines @@
   String visitTypeTestViaFlag(TypeTestViaFlag node) {
     String interceptor = access(node.interceptor);
     return '(TypeTestViaFlag $interceptor ${node.dartType})';
   }
 
   String visitLiteralList(LiteralList node) {
     String values = node.values.map(access).join(' ');
     return '(LiteralList ($values))';
   }
 
-  String visitLiteralMap(LiteralMap node) {
-    String keys = node.entries.map((e) => access(e.key)).join(' ');
-    String values = node.entries.map((e) => access(e.value)).join(' ');
-    return '(LiteralMap ($keys) ($values))';
-  }
-
   String visitSetField(SetField node) {
     String object = access(node.object);
     String field = node.field.name;
     String value = access(node.value);
     return '(SetField $object $field $value)';
   }
 
   String visitGetField(GetField node) {
     String object = access(node.object);
     String field = node.field.name;
@@ skipping 222 matching lines @@
   void setReturnContinuation(Continuation node) {
     assert(!_names.containsKey(node) || _names[node] == 'return');
     _names[node] = 'return';
   }
 
   String getName(Node node) {
     if (!_names.containsKey(node)) return 'MISSING_NAME';
     return _names[node];
   }
 }