Fix a bug in ParallelMoveResolver::AllocateScratchRegister, where we end up allocating PC on ARM.

runtime/vm/flow_graph_compiler.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_FLOW_GRAPH_COMPILER_H_
 #define VM_FLOW_GRAPH_COMPILER_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 #include "vm/code_descriptors.h"
@@ skipping 44 matching lines @@
    private:
     ParallelMoveResolver* resolver_;
     Register reg_;
     bool spilled_;
   };
 
 
   bool IsScratchLocation(Location loc);
   intptr_t AllocateScratchRegister(Location::Kind kind,
                                    intptr_t blocked,
-                                   intptr_t register_count,
+                                   intptr_t first_free_register,
+                                   intptr_t last_free_register,
                                    bool* spilled);
 
   void SpillScratch(Register reg);
   void RestoreScratch(Register reg);
   void SpillFpuScratch(FpuRegister reg);
   void RestoreFpuScratch(FpuRegister reg);
 
   // friend class ScratchXmmRegisterScope;
 
   // Build the initial list of moves.
@@ skipping 525 matching lines @@
   intptr_t entry_patch_pc_offset_;
   intptr_t patch_code_pc_offset_;
   intptr_t lazy_deopt_pc_offset_;
 
   DISALLOW_COPY_AND_ASSIGN(FlowGraphCompiler);
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_COMPILER_H_