Move megamorphic cache table into the Dart heap.

runtime/vm/object_store.cc

Index: runtime/vm/object_store.cc
diff --git a/runtime/vm/object_store.cc b/runtime/vm/object_store.cc
index 25469daa5b969fb6c5b3da8e74a12311f7fe2e1d..c1de3a5e82cad3017265a0b8852f41a65ab7b647 100644
--- a/runtime/vm/object_store.cc
+++ b/runtime/vm/object_store.cc
@@ -88,7 +88,9 @@ ObjectStore::ObjectStore()
     empty_uint32_array_(TypedData::null()),
     handle_message_function_(Function::null()),
     library_load_error_table_(Array::null()),
-    compile_time_constants_(Array::null()) {
+    compile_time_constants_(Array::null()),
+    megamorphic_cache_table_(GrowableObjectArray::null()),
+    megamorphic_miss_handler_(Function::null()) {
   for (RawObject** current = from(); current <= to(); current++) {
     ASSERT(*current == Object::null());
   }