VM-internalize the default Map implementation.

runtime/vm/raw_object.h

Index: runtime/vm/raw_object.h
diff --git a/runtime/vm/raw_object.h b/runtime/vm/raw_object.h
index 6af4f0b1734bf9f36362f968a9617145e0d1bca0..f571979ac5c49fb1421365a4ad4aab9f5933f812 100644
--- a/runtime/vm/raw_object.h
+++ b/runtime/vm/raw_object.h
@@ -1698,12 +1698,16 @@ class RawLinkedHashMap : public RawInstance {
     return reinterpret_cast<RawObject**>(&ptr()->type_arguments_);
   }
   RawTypeArguments* type_arguments_;
-  RawInstance* cme_mark_;
+  RawTypedData* index_;
+  RawSmi* hash_mask_;
   RawArray* data_;
+  RawSmi* used_data_;
+  RawSmi* deleted_keys_;
   RawObject** to() {
-    return reinterpret_cast<RawObject**>(&ptr()->data_);
+    return reinterpret_cast<RawObject**>(&ptr()->deleted_keys_);
   }
 
+
   friend class SnapshotReader;
 };