Fail new space promotions only when old space is truly exhausted.

runtime/vm/heap.h

 // 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.
 
 #ifndef VM_HEAP_H_
 #define VM_HEAP_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/flags.h"
@@ skipping 147 matching lines @@
   // replaced.  A value of NULL disassociate an object from its peer.
   void SetPeer(RawObject* raw_obj, void* peer);
 
   // Retrieves the peer associated with an object.  Returns NULL if
   // there is no association.
   void* GetPeer(RawObject* raw_obj);
 
   // Returns the number of objects with a peer.
   int64_t PeerCount() const;
 
+  PageSpace* old_space() { return old_space_; }
+
  private:
   Heap();
 
   uword AllocateNew(intptr_t size);
   uword AllocateOld(intptr_t size, HeapPage::PageType type);
 
   // The different spaces used for allocation.
   Scavenger* new_space_;
   PageSpace* old_space_;
 
@@ skipping 18 matching lines @@
  public:
   NoGCScope() {}
  private:
   DISALLOW_COPY_AND_ASSIGN(NoGCScope);
 };
 #endif  // defined(DEBUG)
 
 }  // namespace dart
 
 #endif  // VM_HEAP_H_