Clean up hash creation code to use Handle<Smi> where possible

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 0fd3daedb35f8563a2f5ab39445b4c7cd4175c51..f9ea1e479d76b521e97b613283adf104aaefe5e8 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1502,10 +1502,7 @@ class Object {
   // Returns the permanent hash code associated with this object depending on
   // the actual object type. May create and store a hash code if needed and none
   // exists.
-  // TODO(rafaelw): Remove isolate parameter when objects.cc is fully
-  // handlified.
-  static Handle<Object> GetOrCreateHash(Handle<Object> object,
-                                        Isolate* isolate);
+  static Handle<Smi> GetOrCreateHash(Isolate* isolate, Handle<Object> object);
 
   // Checks whether this object has the same value as the given one.  This
   // function is implemented according to ES5, section 9.12 and can be used
@@ -1971,7 +1968,7 @@ class JSReceiver: public HeapObject {
 
   // Retrieves a permanent object identity hash code. May create and store a
   // hash code if needed and none exists.
-  inline static Handle<Object> GetOrCreateIdentityHash(
+  inline static Handle<Smi> GetOrCreateIdentityHash(
       Handle<JSReceiver> object);
 
   // Lookup a property.  If found, the result is valid and has
@@ -2883,7 +2880,7 @@ class JSObject: public JSReceiver {
 
   MUST_USE_RESULT Object* GetIdentityHash();
 
-  static Handle<Object> GetOrCreateIdentityHash(Handle<JSObject> object);
+  static Handle<Smi> GetOrCreateIdentityHash(Handle<JSObject> object);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSObject);
 };
@@ -9873,7 +9870,7 @@ class JSProxy: public JSReceiver {
 
   MUST_USE_RESULT Object* GetIdentityHash();
 
-  static Handle<Object> GetOrCreateIdentityHash(Handle<JSProxy> proxy);
+  static Handle<Smi> GetOrCreateIdentityHash(Handle<JSProxy> proxy);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSProxy);
 };