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

src/heap/spaces.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
 #include "src/allocation.h"
 #include "src/atomic-utils.h"
 #include "src/base/atomicops.h"
@@ skipping 2532 matching lines @@
            from_space_.InitialTotalCapacity());
     return to_space_.InitialTotalCapacity();
   }
 
   // Return the address of the allocation pointer in the active semispace.
   Address top() {
     DCHECK(to_space_.current_page()->ContainsLimit(allocation_info_.top()));
     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()));
     return allocation_info_.limit();
   }
 
   // Return the address of the first object in the active semispace.
   Address bottom() { return to_space_.space_start(); }
 
   // Get the age mark of the inactive semispace.
@@ skipping 407 matching lines @@
     count = 0;
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_SPACES_H_