Address review comments from a previous CL.

vm/object.h

Index: vm/object.h
===================================================================
--- vm/object.h	(revision 9828)
+++ vm/object.h	(working copy)
@@ -142,41 +142,11 @@
 
 class Object {
  public:
-  // Index for Singleton internal VM classes,
-  // this index is used in snapshots to refer to these classes directly.
+  // Index for Singleton internal objects,
+  // this index is used in snapshots to refer to these objects directly.
   enum {
-    kNullObject = 0,
+    kNullObject = kNumPredefinedKinds,
     kSentinelObject,
-    kClassClass,
-    kNullClass,
-    kDynamicClass,
-    kVoidClass,
-    kUnresolvedClassClass,
-    kTypeClass,
-    kTypeParameterClass,
-    kTypeArgumentsClass,
-    kInstantiatedTypeArgumentsClass,
-    kFunctionClass,
-    kFieldClass,
-    kLiteralTokenClass,
-    kTokenStreamClass,
-    kScriptClass,
-    kLibraryClass,
-    kLibraryPrefixClass,
-    kCodeClass,
-    kInstructionsClass,
-    kPcDescriptorsClass,
-    kStackmapClass,
-    kLocalVarDescriptorsClass,
-    kExceptionHandlersClass,
-    kContextClass,
-    kContextScopeClass,
-    kICDataClass,
-    kSubtypeTestCacheClass,
-    kApiErrorClass,
-    kLanguageErrorClass,
-    kUnhandledExceptionClass,
-    kUnwindErrorClass,
     kMaxId,
     kInvalidIndex = -1,
   };
@@ -319,8 +289,7 @@
   static RawClass* icdata_class() { return icdata_class_; }
   static RawClass* subtypetestcache_class() { return subtypetestcache_class_; }
 
-  static int GetSingletonClassIndex(const RawClass* raw_class);
-  static RawClass* GetSingletonClass(int index);
+  static int GetSingletonClassIndex(const RawObject* raw_object);
   static const char* GetSingletonClassName(int index);
 
   static RawClass* CreateAndRegisterInterface(const char* cname,