Implemented the RoundUint64ToFloat64 TurboFan operator for x64 and arm64.

src/compiler/arm64/instruction-selector-arm64.cc

Index: src/compiler/arm64/instruction-selector-arm64.cc
diff --git a/src/compiler/arm64/instruction-selector-arm64.cc b/src/compiler/arm64/instruction-selector-arm64.cc
index 6abad0aa923dc6f05b1befed6164147100de8f37..3149566a56f8fafd632c75ef29a55941e666fcee 100644
--- a/src/compiler/arm64/instruction-selector-arm64.cc
+++ b/src/compiler/arm64/instruction-selector-arm64.cc
@@ -1326,6 +1326,11 @@ void InstructionSelector::VisitRoundInt64ToFloat64(Node* node) {
 }
 
 
+void InstructionSelector::VisitRoundUint64ToFloat64(Node* node) {
+  VisitRR(this, kArm64Uint64ToFloat64, node);
+}
+
+
 void InstructionSelector::VisitBitcastFloat32ToInt32(Node* node) {
   VisitRR(this, kArm64Float64ExtractLowWord32, node);
 }