Fix unsafe cast in RegExpStack

Review URL: http://codereview.chromium.org/164552


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2690 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/regexp-stack.h

@@ -74,7 +74,7 @@ class RegExpStack {
 
  private:
   // Artificial limit used when no memory has been allocated.
-  static const uintptr_t kMemoryTop = -1;
+  static const uintptr_t kMemoryTop = static_cast<uintptr_t>(-1);
 
   // Minimal size of allocated stack area.
   static const size_t kMinimumStackSize = 1 * KB;