[heap] Remove black pages and use black areas instead.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 0f7660a71a295e820c9073ef0c6fff457ac930bc..7cca4ad958f31d4598bea62eb2d16200c0faee68 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -1994,10 +1994,9 @@ void WeakCell::initialize(HeapObject* val) {
   // We just have to execute the generational barrier here because we never
   // mark through a weak cell and collect evacuation candidates when we process
   // all weak cells.
-  WriteBarrierMode mode =
-      Page::FromAddress(this->address())->IsFlagSet(Page::BLACK_PAGE)
-          ? UPDATE_WRITE_BARRIER
-          : UPDATE_WEAK_WRITE_BARRIER;
+  WriteBarrierMode mode = Marking::IsBlack(ObjectMarking::MarkBitFrom(this))
+                              ? UPDATE_WRITE_BARRIER
+                              : UPDATE_WEAK_WRITE_BARRIER;
   CONDITIONAL_WRITE_BARRIER(GetHeap(), this, kValueOffset, val, mode);
 }