Never try to add 0 bytes to free list.

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/compiler_stats.h"
 #include "vm/gc_marker.h"
 #include "vm/gc_sweeper.h"
@@ skipping 202 matching lines @@
     if ((result == 0) &&
         (page_space_controller_.CanGrowPageSpace(size) ||
          growth_policy == kForceGrowth) &&
         CanIncreaseCapacity(kPageSize)) {
       HeapPage* page = AllocatePage(type);
       ASSERT(page != NULL);
       // Start of the newly allocated page is the allocated object.
       result = page->object_start();
       // Enqueue the remainder in the free list.
       uword free_start = result + size;
-      freelist_[type].Free(free_start, page->object_end() - free_start);
+      intptr_t free_size = page->object_end() - free_start;
+      if (free_size > 0) {
+        freelist_[type].Free(free_start, free_size);
+      }
     }
   } else {
     // Large page allocation.
     intptr_t page_size = LargePageSizeFor(size);
     if (page_size < size) {
       // On overflow we fail to allocate.
       return 0;
     }
     if (CanIncreaseCapacity(page_size)) {
       HeapPage* page = AllocateLargePage(size, type);
@@ skipping 389 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