Make HashMap a template class to specify the allocation policy.

src/log.h

Index: src/log.h
===================================================================
--- src/log.h	(revision 10795)
+++ src/log.h	(working copy)
@@ -1,4 +1,4 @@
-// Copyright 2011 the V8 project authors. All rights reserved.
+// Copyright 2012 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:
@@ -71,7 +71,6 @@
 // tick profiler requires code events, so --prof implies --log-code.
 
 // Forward declarations.
-class HashMap;
 class LogMessageBuilder;
 class Profiler;
 class Semaphore;