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 217f30f4bf54851e7e75a45ce60e0de3add2c71d..3183d7bcd66dadb54c3e53e1b9542700ed5ffc7b 100644
--- a/runtime/vm/raw_object.h
+++ b/runtime/vm/raw_object.h
@@ -1689,12 +1689,16 @@ 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;
 };