Allow compiling with strict aliasing enabled on GCC 4.4.

src/top.cc

 // Copyright 2006-2008 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 89 matching lines @@
 
 void Top::IterateThread(ThreadVisitor* v, char* t) {
   ThreadLocalTop* thread = reinterpret_cast<ThreadLocalTop*>(t);
   v->VisitThread(thread);
 }
 
 
 void Top::Iterate(ObjectVisitor* v, ThreadLocalTop* thread) {
   v->VisitPointer(&(thread->pending_exception_));
   v->VisitPointer(&(thread->pending_message_obj_));
-  v->VisitPointer(
-      BitCast<Object**, Script**>(&(thread->pending_message_script_)));
-  v->VisitPointer(BitCast<Object**, Context**>(&(thread->context_)));
+  v->VisitPointer(BitCast<Object**>(&(thread->pending_message_script_)));
+  v->VisitPointer(BitCast<Object**>(&(thread->context_)));
   v->VisitPointer(&(thread->scheduled_exception_));
 
   for (v8::TryCatch* block = thread->TryCatchHandler();
        block != NULL;
        block = TRY_CATCH_FROM_ADDRESS(block->next_)) {
-    v->VisitPointer(BitCast<Object**, void**>(&(block->exception_)));
-    v->VisitPointer(BitCast<Object**, void**>(&(block->message_)));
+    v->VisitPointer(BitCast<Object**>(&(block->exception_)));
+    v->VisitPointer(BitCast<Object**>(&(block->message_)));
   }
 
   // Iterate over pointers on native execution stack.
   for (StackFrameIterator it(thread); !it.done(); it.Advance()) {
     it.frame()->Iterate(v);
   }
 }
 
 
 void Top::Iterate(ObjectVisitor* v) {
@@ skipping 928 matching lines @@
   Top::break_access_->Lock();
 }
 
 
 ExecutionAccess::~ExecutionAccess() {
   Top::break_access_->Unlock();
 }
 
 
 } }  // namespace v8::internal