Give uses within a loop a greater weight when doing representation inference.

src/hydrogen.cc

Index: src/hydrogen.cc
===================================================================
--- src/hydrogen.cc	(revision 9619)
+++ src/hydrogen.cc	(working copy)
@@ -1652,7 +1652,7 @@
     Representation rep = use->RequiredInputRepresentation(it.index());
     if (rep.IsNone()) continue;
     if (use->IsPhi()) HPhi::cast(use)->AddIndirectUsesTo(&use_count[0]);
-    ++use_count[rep.kind()];
+    use_count[rep.kind()] += use->LoopWeight();
   }
   int tagged_count = use_count[Representation::kTagged];
   int double_count = use_count[Representation::kDouble];