Implement weak persistent handles in the Dart API.

runtime/vm/raw_object.cc

 // Copyright (c) 2011, 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/raw_object.h"
 
 #include "vm/freelist.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
 #include "vm/visitor.h"
@@ skipping 124 matching lines @@
         instance_size = ExceptionHandlers::InstanceSize(num_handlers);
         break;
       }
       case kJSRegExp: {
         const RawJSRegExp* raw_jsregexp =
             reinterpret_cast<const RawJSRegExp*>(this);
         intptr_t data_length = Smi::Value(raw_jsregexp->ptr()->data_length_);
         instance_size = JSRegExp::InstanceSize(data_length);
         break;
       }
+      case kFreeListElement: {
+        uword addr = RawObject::ToAddr(const_cast<RawObject*>(this));
+        FreeListElement* element = reinterpret_cast<FreeListElement*>(addr);
+        instance_size = element->Size();
+        break;
+      }
       default:
         UNREACHABLE();
         break;
     }
   }
   ASSERT(instance_size != 0);
   return instance_size;
 }
 
 
@@ skipping 407 matching lines @@
 intptr_t RawJSRegExp::VisitJSRegExpPointers(RawJSRegExp* raw_obj,
                                             ObjectPointerVisitor* visitor) {
   // Make sure that we got here with the tagged pointer as this.
   ASSERT(raw_obj->IsHeapObject());
   intptr_t length = Smi::Value(raw_obj->ptr()->data_length_);
   visitor->VisitPointers(raw_obj->from(), raw_obj->to());
   return JSRegExp::InstanceSize(length);
 }
 
 }  // namespace dart