Small simplification of #include dependencies.

src/heap.h

 // 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 13 matching lines @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #ifndef V8_HEAP_H_
 #define V8_HEAP_H_
 
 #include <math.h>
 
 #include "splay-tree-inl.h"
-#include "zone-inl.h"
-
+#include "v8-counters.h"
 
 namespace v8 {
 namespace internal {
 
+// Forward declarations.
+class ZoneScopeInfo;
+
 // Defines all the roots in Heap.
 #define UNCONDITIONAL_STRONG_ROOT_LIST(V)                                      \
   /* Put the byte array map early.  We need it to be in place by the time   */ \
   /* the deserializer hits the next page, since it wants to put a byte      */ \
   /* array in the unused space at the end of the page.                      */ \
   V(Map, byte_array_map, ByteArrayMap)                                         \
   V(Map, one_pointer_filler_map, OnePointerFillerMap)                          \
   V(Map, two_pointer_filler_map, TwoPointerFillerMap)                          \
   /* Cluster the most popular ones in a few cache lines here at the top.    */ \
   V(Smi, stack_limit, StackLimit)                                              \
@@ skipping 1686 matching lines @@
 
   // To speed up scavenge collections new space string are kept
   // separate from old space strings.
   static List<Object*> new_space_strings_;
   static List<Object*> old_space_strings_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_