Unify processing of weak lists in heap.cc

test/cctest/test-weaktypedarrays.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 26 matching lines @@
 using namespace v8::internal;
 
 static Isolate* GetIsolateFrom(LocalContext* context) {
   return reinterpret_cast<Isolate*>((*context)->GetIsolate());
 }
 
 
 static int CountArrayBuffersInWeakList(Heap* heap) {
   int count = 0;
   for (Object* o = heap->array_buffers_list();
-       o != Smi::FromInt(0);
+       !o->IsUndefined();
        o = JSArrayBuffer::cast(o)->weak_next()) {
     count++;
   }
   return count;
 }
 
 
 static bool HasArrayBufferInWeakList(Heap* heap, JSArrayBuffer* ab) {
   for (Object* o = heap->array_buffers_list();
-       o != Smi::FromInt(0);
+       !o->IsUndefined();
        o = JSArrayBuffer::cast(o)->weak_next()) {
     if (ab == o) return true;
   }
   return false;
 }
 
 
 static int CountTypedArrays(JSArrayBuffer* array_buffer) {
   int count = 0;
   for (Object* o = array_buffer->weak_first_array();
-       o != Smi::FromInt(0);
+       !o->IsUndefined();
        o = JSTypedArray::cast(o)->weak_next()) {
     count++;
   }
 
   return count;
 }
 
 static bool HasTypedArrayInWeakList(JSArrayBuffer* array_buffer,
                                     JSTypedArray* ta) {
   for (Object* o = array_buffer->weak_first_array();
-       o != Smi::FromInt(0);
+       !o->IsUndefined();
        o = JSTypedArray::cast(o)->weak_next()) {
     if (ta == o) return true;
   }
   return false;
 }
 
 
 TEST(WeakArrayBuffersFromApi) {
   v8::V8::Initialize();
   LocalContext context;
@@ skipping 281 matching lines @@
 
 TEST(Float64ArrayFromScript) {
   TestTypedArrayFromScript<v8::Float64Array>("Float64Array");
 }
 
 
 TEST(Uint8ClampedArrayFromScript) {
   TestTypedArrayFromScript<v8::Uint8ClampedArray>("Uint8ClampedArray");
 }