Fix PathTracer.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index 8956e3c56b50f31af04c57a3caf9669d4c58f3f2..c7a7c82aa65c17252f376a681f9b318f40078493 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -2717,6 +2717,9 @@ class PathTracer : public ObjectVisitor {
     FIND_FIRST  // Will stop the search after first match.
   };
 
+  // Tags 0, 1, and 3 are used. Use 2 for marking visited HeapObject.
+  static const int kMarkTag = 2;
+
   // For the WhatToFind arg, if FIND_FIRST is specified, tracing will stop
   // after the first match.  If FIND_ALL is specified, then tracing will be
   // done for all matches.
@@ -2748,9 +2751,6 @@ class PathTracer : public ObjectVisitor {
   void UnmarkRecursively(Object** p, UnmarkVisitor* unmark_visitor);
   virtual void ProcessResults();
 
-  // Tags 0, 1, and 3 are used. Use 2 for marking visited HeapObject.
-  static const int kMarkTag = 2;
-
   Object* search_target_;
   bool found_target_;
   bool found_target_in_trace_;