[serializer] small fixes for blink snapshot.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 22888fc7f2e90e1b07a380208a79a27689402bc7..33e395f8ecc70a8d4468b941b3204f83030b6e9a 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -34,6 +34,7 @@ class RandomNumberGenerator;
 namespace internal {
 
 class AccessCompilerData;
+class AddressToIndexHashMap;
 class BasicBlockProfiler;
 class Bootstrapper;
 class CancelableTaskManager;
@@ -59,6 +60,7 @@ class ExternalCallbackScope;
 class ExternalReferenceTable;
 class Factory;
 class HandleScopeImplementer;
+class HeapObjectToIndexHashMap;
 class HeapProfiler;
 class HStatistics;
 class HTracer;
@@ -400,8 +402,8 @@ typedef List<HeapObject*> DebugObjectCache;
   V(Object*, string_stream_current_security_token, nullptr)                   \
   V(ExternalReferenceTable*, external_reference_table, nullptr)               \
   V(intptr_t*, api_external_references, nullptr)                              \
-  V(base::HashMap*, external_reference_map, nullptr)                          \
-  V(base::HashMap*, root_index_map, nullptr)                                  \
+  V(AddressToIndexHashMap*, external_reference_map, nullptr)                  \
+  V(HeapObjectToIndexHashMap*, root_index_map, nullptr)                       \
   V(v8::DeserializeInternalFieldsCallback,                                    \
     deserialize_internal_fields_callback, nullptr)                            \
   V(int, pending_microtask_count, 0)                                          \