Adds ldr and str to arm64.

runtime/vm/simulator_arm64.h

Index: runtime/vm/simulator_arm64.h
===================================================================
--- runtime/vm/simulator_arm64.h	(revision 34829)
+++ runtime/vm/simulator_arm64.h	(working copy)
@@ -108,12 +108,30 @@
   }
   void HandleIllegalAccess(uword addr, Instr* instr);
 
+  // Handles an unaligned memory access.
+  void UnalignedAccess(const char* msg, uword addr, Instr* instr);
+
   // Handles a legal instruction that the simulator does not implement.
   void UnimplementedInstruction(Instr* instr);
 
   // Unsupported instructions use Format to print an error and stop execution.
   void Format(Instr* instr, const char* format);
 
+  inline uint8_t ReadBU(uword addr);
+  inline int8_t ReadB(uword addr);
+  inline void WriteB(uword addr, uint8_t value);
+
+  inline uint16_t ReadHU(uword addr, Instr* instr);
+  inline int16_t ReadH(uword addr, Instr* instr);
+  inline void WriteH(uword addr, uint16_t value, Instr* instr);
+
+  inline uint32_t ReadWU(uword addr, Instr* instr);
+  inline int32_t ReadW(uword addr, Instr* instr);
+  inline void WriteW(uword addr, uint32_t value, Instr* instr);
+
+  inline intptr_t ReadX(uword addr, Instr* instr);
+  inline void WriteX(uword addr, intptr_t value, Instr* instr);
+
   // Helper functions to set the conditional flags in the architecture state.
   void SetNZFlagsW(int32_t val);
   bool CarryFromW(int32_t left, int32_t right);