MIPS64: Implemented the RoundUint64ToFloat64 TurboFan operator for x64 and arm64.

src/mips64/macro-assembler-mips64.h

Index: src/mips64/macro-assembler-mips64.h
diff --git a/src/mips64/macro-assembler-mips64.h b/src/mips64/macro-assembler-mips64.h
index fa3808fa7454736de1c81c13907ff2bda77d83f0..9dedf4899fe247049d04d0677948e4555af0c866 100644
--- a/src/mips64/macro-assembler-mips64.h
+++ b/src/mips64/macro-assembler-mips64.h
@@ -821,6 +821,10 @@ class MacroAssembler: public Assembler {
   void Cvt_d_uw(FPURegister fd, FPURegister fs, FPURegister scratch);
   void Cvt_d_uw(FPURegister fd, Register rs, FPURegister scratch);
 
+  // Convert unsigned long to double.
+  void Cvt_d_ul(FPURegister fd, FPURegister fs);
+  void Cvt_d_ul(FPURegister fd, Register rs);
+
   // Convert double to unsigned long.
   void Trunc_l_ud(FPURegister fd, FPURegister fs, FPURegister scratch);