Add new HSeqStringGetChar instruction.

src/x64/assembler-x64.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 680 matching lines @@
   void leave();
 
   // Moves
   void movb(Register dst, const Operand& src);
   void movb(Register dst, Immediate imm);
   void movb(const Operand& dst, Register src);
   void movb(const Operand& dst, Immediate imm);
 
   // Move the low 16 bits of a 64-bit register value to a 16-bit
   // memory location.
+  void movw(Register dst, const Operand& src);
   void movw(const Operand& dst, Register src);
   void movw(const Operand& dst, Immediate imm);
 
   void movl(Register dst, Register src);
   void movl(Register dst, const Operand& src);
   void movl(const Operand& dst, Register src);
   void movl(const Operand& dst, Immediate imm);
   // Load a 32-bit immediate value, zero-extended to 64 bits.
   void movl(Register dst, Immediate imm32);
 
@@ skipping 994 matching lines @@
  private:
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_ASSEMBLER_X64_H_