Lower map literals to constructor or function calls in builder

pkg/compiler/lib/src/tree_ir/optimization/pull_into_initializers.dart

 // Copyright (c) 2015, 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 tree_ir.optimization.pull_into_initializers;
 
 import 'optimization.dart' show Pass;
 import '../tree_ir_nodes.dart';
 
 /// Where a variable has been assigned.
@@ skipping 274 matching lines @@
   }
 
   Expression visitLiteralList(LiteralList node) {
     super.visitLiteralList(node);
     if (node.type != null) {
       ++impureCounter; // Type casts can throw.
     }
     return node;
   }
 
-  Expression visitLiteralMap(LiteralMap node) {
-    super.visitLiteralMap(node);
-    if (node.type != null) {
-      ++impureCounter; // Type casts can throw.
-    }
-    return node;
-  }
-
   Expression visitTypeOperator(TypeOperator node) {
     super.visitTypeOperator(node);
     if (!node.isTypeTest) {
       ++impureCounter; // Type casts can throw.
     }
     return node;
   }
 
   Expression visitGetField(GetField node) {
     super.visitGetField(node);
@@ skipping 59 matching lines @@
 
   @override
   Expression visitForeignExpression(ForeignExpression node) {
     rewriteList(node.arguments);
     if (node.nativeBehavior.sideEffects.hasSideEffects()) {
       ++impureCounter;
     }
     return node;
   }
 }