[heap] Cleanup: remove unused declaration

R=ulan@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1510213002

Cr-Commit-Position: refs/heads/master@{#32739}

src/heap/store-buffer.h

@@ -19,9 +19,6 @@ class StoreBuffer;
 
 typedef void (*ObjectSlotCallback)(HeapObject** from, HeapObject* to);
 
-typedef void (StoreBuffer::*RegionCallback)(Address start, Address end,
-                                            ObjectSlotCallback slot_callback);
-
 // Used to implement the write barrier by collecting addresses of pointers
 // between spaces.
 class StoreBuffer {
@@ -147,15 +144,6 @@ class StoreBuffer {
   void FindPointersToNewSpaceInRegion(Address start, Address end,
                                       ObjectSlotCallback slot_callback);
 
-  // For each region of pointers on a page in use from an old space call
-  // visit_pointer_region callback.
-  // If either visit_pointer_region or callback can cause an allocation
-  // in old space and changes in allocation watermark then
-  // can_preallocate_during_iteration should be set to true.
-  void IteratePointersOnPage(PagedSpace* space, Page* page,
-                             RegionCallback region_callback,
-                             ObjectSlotCallback slot_callback);
-
   void IteratePointersInStoreBuffer(ObjectSlotCallback slot_callback);
 
 #ifdef VERIFY_HEAP