[heap] Remove NewSpace::set_top and the corresponding hack

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 2cea06673abf136a0e3b013680e2cc6d59418e71..222380856bfe7286b50a63eee2e37544a1f7e512 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -2550,11 +2550,6 @@ class NewSpace : public Space {
     return allocation_info_.top();
   }
 
-  void set_top(Address top) {
-    DCHECK(to_space_.current_page()->ContainsLimit(top));
-    allocation_info_.set_top(top);
-  }
-
   // Return the address of the allocation pointer limit in the active semispace.
   Address limit() {
     DCHECK(to_space_.current_page()->ContainsLimit(allocation_info_.limit()));