Use the new introduced block's reachable flag.

BUG=
R=verwaest@chromium.org

Review URL: https://chromiumcodereview.appspot.com/26459002

Patch from Weiliang Lin <weiliang.lin2@gmail.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17129 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.cc

@@ -4037,7 +4037,7 @@ Representation HValue::RepresentationFromUseRequirements() {
   Representation rep = Representation::None();
   for (HUseIterator it(uses()); !it.Done(); it.Advance()) {
     // Ignore the use requirement from never run code
-    if (it.value()->block()->IsDeoptimizing()) continue;
+    if (it.value()->block()->IsUnreachable()) continue;
 
     // We check for observed_input_representation elsewhere.
     Representation use_rep =