Implement optional turbofan UnalignedLoad and UnalignedStore operators

src/mips64/assembler-mips64.h

Index: src/mips64/assembler-mips64.h
diff --git a/src/mips64/assembler-mips64.h b/src/mips64/assembler-mips64.h
index de09366b427865870ab2eed1860cc6a3f7f14501..5a2033acc14a1b2f4f3d349fc01698f6fcdb6753 100644
--- a/src/mips64/assembler-mips64.h
+++ b/src/mips64/assembler-mips64.h
@@ -1217,6 +1217,9 @@ class Assembler : public AssemblerBase {
   void lsa(Register rd, Register rt, Register rs, uint8_t sa);
   void dlsa(Register rd, Register rt, Register rs, uint8_t sa);
 
+  // Helpers.
+  void LoadRegPlusOffsetToAt(const MemOperand& src);
+
   // Relocation for a type-recording IC has the AST id added to it.  This
   // member variable is a way to pass the information from the call site to
   // the relocation info.
@@ -1413,9 +1416,6 @@ class Assembler : public AssemblerBase {
   void GenInstrJump(Opcode opcode,
                      uint32_t address);
 
-  // Helpers.
-  void LoadRegPlusOffsetToAt(const MemOperand& src);
-
   // Labels.
   void print(Label* L);
   void bind_to(Label* L, int pos);