Remove grab-bag includes of v8.h from regexp engine.

src/regexp/regexp-stack.cc

Index: src/regexp/regexp-stack.cc
diff --git a/src/regexp/regexp-stack.cc b/src/regexp/regexp-stack.cc
index 35a58e1e5331d3d02f2f73d957a223b69e7a3223..348e6841515ce054d3359f9f98a8c810847d93bf 100644
--- a/src/regexp/regexp-stack.cc
+++ b/src/regexp/regexp-stack.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/regexp/regexp-stack.h"
 
+#include "src/isolate.h"
+#include "src/objects-inl.h"  // TODO(mstarzinger): Temporary cycle breaker!
+
 namespace v8 {
 namespace internal {