remove V8_USE_UNSAFE_HANDLES define

R=svenpanne@chromium.org
BUG=

Review URL: https://codereview.chromium.org/16896004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15142 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8.h

@@ -220,8 +220,6 @@ class WeakReferenceCallbacks {
   }
 
 
-#define V8_USE_UNSAFE_HANDLES
-
 /**
  * An object reference managed by the v8 garbage collector.
  *