H-BuildIncrement should make use of available type feedback

src/hydrogen.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1040 matching lines @@
   HInstruction* AddUncasted(P1 p1, P2 p2) {
     HInstruction* result = AddInstruction(NewUncasted<I>(p1, p2));
     // Specializations must have their parameters properly casted
     // to avoid landing here.
     ASSERT(!result->IsSimulate());
     return result;
   }
 
   template<class I, class P1, class P2>
   I* Add(P1 p1, P2 p2) {
-    return static_cast<I*>(AddUncasted<I>(p1, p2));
+    return I::cast(AddUncasted<I>(p1, p2));
   }
 
   template<class I, class P1, class P2, class P3>
   HInstruction* NewUncasted(P1 p1, P2 p2, P3 p3) {
     return I::New(zone(), context(), p1, p2, p3);
   }
 
   template<class I, class P1, class P2, class P3>
   I* New(P1 p1, P2 p2, P3 p3) {
     return I::cast(NewUncasted<I>(p1, p2, p3));
@@ skipping 1236 matching lines @@
   }
 
  private:
   HGraphBuilder* builder_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_