Lower map literals to constructor or function calls in builder

pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart

Index: pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart
diff --git a/pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart b/pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart
index 979647ac22a0f79b822200bba8dac7af5b0dfd3e..d6f17694116388573ef87ad37ea3984f1d9ba4d6 100644
--- a/pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart
+++ b/pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart
@@ -414,16 +414,6 @@ class SubexpressionVisitor extends ExpressionVisitor<String> {
     return "list [$values]";
   }
 
-  String visitLiteralMap(LiteralMap node) {
-    List<String> entries = new List<String>();
-    node.entries.forEach((LiteralMapEntry entry) {
-      String key = visitExpression(entry.key);
-      String value = visitExpression(entry.value);
-      entries.add("$key: $value");
-    });
-    return "map [${entries.join(', ')}]";
-  }
-
   String visitConstant(Constant node) {
     return "${node.value.toStructuredString()}";
   }