Guard against rare case of allocation failure during evacuation.

src/spaces.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 703 matching lines @@
   for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next()) {
     Address cur = obj->address();
     Address next = cur + obj->Size();
     if ((cur <= addr) && (addr < next)) return obj;
   }
 
   UNREACHABLE();
   return Failure::Exception();
 }
 
-
-bool PagedSpace::Expand() {
+bool PagedSpace::CanExpand() {
   ASSERT(max_capacity_ % Page::kObjectAreaSize == 0);
   ASSERT(Capacity() % Page::kObjectAreaSize == 0);
 
   if (Capacity() == max_capacity_) return false;
 
   ASSERT(Capacity() < max_capacity_);
 
   // Are we going to exceed capacity for this space?
   if ((Capacity() + Page::kPageSize) > max_capacity_) return false;
 
+  return true;
+}
+
+bool PagedSpace::Expand() {
+  if (!CanExpand()) return false;
+
   Page* p = heap()->isolate()->memory_allocator()->
       AllocatePage(this, executable());
   if (p == NULL) return false;
 
   ASSERT(Capacity() <= max_capacity_);
 
   p->InsertAfter(anchor_.prev_page());
 
   return true;
 }
@@ skipping 1759 matching lines @@
   for (HeapObject* obj = obj_it.Next(); obj != NULL; obj = obj_it.Next()) {
     if (obj->IsCode()) {
       Code* code = Code::cast(obj);
       isolate->code_kind_statistics()[code->kind()] += code->Size();
     }
   }
 }
 #endif  // DEBUG
 
 } }  // namespace v8::internal