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

src/compiler/mips64/code-generator-mips64.cc

Index: src/compiler/mips64/code-generator-mips64.cc
diff --git a/src/compiler/mips64/code-generator-mips64.cc b/src/compiler/mips64/code-generator-mips64.cc
index 62fd2f5efcf4bab3870f2aefb3cb75f165d454ae..13ee9d0b35058637d40cfe56305a27bf0bee92d9 100644
--- a/src/compiler/mips64/code-generator-mips64.cc
+++ b/src/compiler/mips64/code-generator-mips64.cc
@@ -934,6 +934,10 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       __ Cvt_d_uw(i.OutputDoubleRegister(), i.InputRegister(0), scratch);
       break;
     }
+    case kMips64CvtDUl: {
+      __ Cvt_d_ul(i.OutputDoubleRegister(), i.InputRegister(0));
+      break;
+    }
     case kMips64TruncWD: {
       FPURegister scratch = kScratchDoubleReg;
       // Other arches use round to zero here, so we follow.