Move ReturnInstr to new scheme (x64 and ia32) and implement more code in new ia32 compiler.

runtime/vm/locations.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_LOCATIONS_H_
 #define VM_LOCATIONS_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 #include "vm/bitfield.h"
@@ skipping 131 matching lines @@
     return output_location_;
   }
 
   void set_out(Location loc) {
     output_location_ = loc;
   }
 
   // Perform a greedy local register allocation.  Consider all register free.
   void AllocateRegisters();
 
+  static LocationSummary* Make(intptr_t input_count, Location out);
+
  private:
   // TODO(vegorov): replace with ZoneArray.
   GrowableArray<Location> input_locations_;
   GrowableArray<Location> temp_locations_;
   Location output_location_;
 };
 
 
 }  // namespace dart
 
 #endif  // VM_LOCATIONS_H_