[heap] Remove border page

src/heap/heap-inl.h

Index: src/heap/heap-inl.h
diff --git a/src/heap/heap-inl.h b/src/heap/heap-inl.h
index 9499546850e55f5133daecb1286a52faadcdcb96..dda9a89c988b47349b26d07b7920064d76a82c58 100644
--- a/src/heap/heap-inl.h
+++ b/src/heap/heap-inl.h
@@ -519,9 +519,6 @@ bool Heap::OldGenerationAllocationLimitReached() {
 
 template <PromotionMode promotion_mode>
 bool Heap::ShouldBePromoted(Address old_address, int object_size) {
-  Page* page = Page::FromAddress(old_address);
-  Address age_mark = new_space_->age_mark();
-
   if (promotion_mode == PROMOTE_MARKED) {
     MarkBit mark_bit = ObjectMarking::MarkBitFrom(old_address);
     if (!Marking::IsWhite(mark_bit)) {
@@ -529,8 +526,7 @@ bool Heap::ShouldBePromoted(Address old_address, int object_size) {
     }
   }
 
-  return page->IsFlagSet(MemoryChunk::NEW_SPACE_BELOW_AGE_MARK) &&
-         (!page->ContainsLimit(age_mark) || old_address < age_mark);
+  return Page::FromAddress(old_address)->InIntermediateGeneration();
 }
 
 PromotionMode Heap::CurrentPromotionMode() {
@@ -631,16 +627,8 @@ AllocationMemento* Heap::FindAllocationMemento(HeapObject* object) {
   // Bail out if the memento is below the age mark, which can happen when
   // mementos survived because a page got moved within new space.
   Page* object_page = Page::FromAddress(object_address);
-  if (object_page->IsFlagSet(Page::NEW_SPACE_BELOW_AGE_MARK)) {
-    Address age_mark =
-        reinterpret_cast<SemiSpace*>(object_page->owner())->age_mark();
-    if (!object_page->Contains(age_mark)) {
-      return nullptr;
-    }
-    // Do an exact check in the case where the age mark is on the same page.
-    if (object_address < age_mark) {
-      return nullptr;
-    }
+  if (object_page->InIntermediateGeneration()) {
+    return nullptr;
   }
 
   AllocationMemento* memento_candidate = AllocationMemento::cast(candidate);