Lower map literals to constructor or function calls in builder

pkg/compiler/lib/src/cps_ir/cps_ir_tracer.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_tracer;
 
 import 'dart:async' show EventSink;
 import 'cps_ir_nodes.dart' as cps_ir;
 import '../tracer.dart';
 
@@ skipping 174 matching lines @@
   visitUnreachable(cps_ir.Unreachable node) {
     String dummy = names.name(node);
     printStmt(dummy, 'Unreachable');
   }
 
   visitLiteralList(cps_ir.LiteralList node) {
     String values = node.values.map(formatReference).join(', ');
     return "LiteralList ($values)";
   }
 
-  visitLiteralMap(cps_ir.LiteralMap node) {
-    List<String> entries = new List<String>();
-    for (cps_ir.LiteralMapEntry entry in node.entries) {
-      String key = formatReference(entry.key);
-      String value = formatReference(entry.value);
-      entries.add("$key: $value");
-    }
-    return "LiteralMap (${entries.join(', ')})";
-  }
-
   visitTypeCast(cps_ir.TypeCast node) {
     String value = formatReference(node.value);
     String args = node.typeArguments.map(formatReference).join(', ');
     return "TypeCast ($value ${node.dartType} ($args))";
   }
 
   visitInvokeContinuation(cps_ir.InvokeContinuation node) {
     String dummy = names.name(node);
     String kont = formatReference(node.continuation);
     String args = node.arguments.map(formatReference).join(', ');
@@ skipping 356 matching lines @@
   // Primitives and conditions are not visited when searching for blocks.
   unexpectedNode(cps_ir.Node node) {
     throw "The IR tracer's block collector reached an unexpected IR "
         "instruction: $node";
   }
 
   visitLiteralList(cps_ir.LiteralList node) {
     unexpectedNode(node);
   }
 
-  visitLiteralMap(cps_ir.LiteralMap node) {
-    unexpectedNode(node);
-  }
-
   visitConstant(cps_ir.Constant node) {
     unexpectedNode(node);
   }
 
   visitGetMutable(cps_ir.GetMutable node) {
     unexpectedNode(node);
   }
 
   visitParameter(cps_ir.Parameter node) {
     unexpectedNode(node);
@@ skipping 96 matching lines @@
   }
 
   visitBoundsCheck(cps_ir.BoundsCheck node) {
     unexpectedNode(node);
   }
 
   visitNullCheck(cps_ir.NullCheck node) {
     unexpectedNode(node);
   }
 }