Fix a build break caused by a type mismatch on 64-bit build targets.

runtime/vm/pages.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/pages.h"
 
 #include "platform/assert.h"
 #include "vm/gc_marker.h"
 #include "vm/gc_sweeper.h"
 #include "vm/object.h"
@@ skipping 514 matching lines @@
                      garbage_collection_time_fraction,
                      garbage_collection_time_ratio_);
       }
       OS::PrintErr("\n");
     }
     if (!enough_free_space) {
       intptr_t growth_target = static_cast<intptr_t>(in_use_after /
                                                      desired_utilization_);
       intptr_t growth_in_bytes = Utils::RoundUp(growth_target - in_use_after,
                                                 PageSpace::kPageSize);
-      intptr_t growth_in_pages = growth_in_bytes / PageSpace::kPageSize;
+      int growth_in_pages = growth_in_bytes / PageSpace::kPageSize;
       grow_heap_ = Utils::Maximum(growth_in_pages, heap_growth_rate_);
     } else {
       grow_heap_ = heap_growth_rate_;
     }
   }
 }
 
 
 PageSpaceGarbageCollectionHistory::PageSpaceGarbageCollectionHistory()
     : index_(0) {
@@ skipping 32 matching lines @@
     return 0;
   } else {
     ASSERT(total_time >= gc_time);
     int result= static_cast<int>((static_cast<double>(gc_time) /
                              static_cast<double>(total_time)) * 100);
     return result;
   }
 }
 
 }  // namespace dart