Remove grab-bag includes of v8.h from heap.

src/heap/identity-map.cc

Index: src/heap/identity-map.cc
diff --git a/src/heap/identity-map.cc b/src/heap/identity-map.cc
index a93f607ee7797e9191a2083ad71f16c543ee48f4..e4ce4e562c9a158c75e451a2b6a6f0b306ce1331 100644
--- a/src/heap/identity-map.cc
+++ b/src/heap/identity-map.cc
@@ -2,10 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "src/v8.h"
+#include "src/heap/identity-map.h"
 
 #include "src/heap/heap.h"
-#include "src/heap/identity-map.h"
+#include "src/objects-inl.h"  // TODO(mstarzinger): Temporary cycle breaker!
+#include "src/zone-containers.h"
 
 namespace v8 {
 namespace internal {