[heap] Modernize all *Page iterators to be proper C++ iterators

src/heap/remembered-set.cc

Index: src/heap/remembered-set.cc
diff --git a/src/heap/remembered-set.cc b/src/heap/remembered-set.cc
index 403c99b05712ec53d2920b40e5ee6ff9e3a2f84c..0bc5e6e32401de0e4566cf81e37e9d23ab67ab04 100644
--- a/src/heap/remembered-set.cc
+++ b/src/heap/remembered-set.cc
@@ -16,10 +16,7 @@ namespace internal {
 template <PointerDirection direction>
 void RememberedSet<direction>::ClearInvalidSlots(Heap* heap) {
   STATIC_ASSERT(direction == OLD_TO_NEW);
-  PageIterator it(heap->old_space());
-  MemoryChunk* chunk;
-  while (it.has_next()) {
-    chunk = it.next();
+  for (MemoryChunk* chunk : *heap->old_space()) {
     SlotSet* slots = GetSlotSet(chunk);
     if (slots != nullptr) {
       slots->Iterate([heap, chunk](Address addr) {