Implemented the RoundUint64ToFloat64 TurboFan operator for x64 and arm64.

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

Index: src/compiler/ppc/instruction-selector-ppc.cc
diff --git a/src/compiler/ppc/instruction-selector-ppc.cc b/src/compiler/ppc/instruction-selector-ppc.cc
index f2a00044c2c2d348b794f4bea83ec44429ba268d..8773273c9007122ecffddb372dd168edfd728f9e 100644
--- a/src/compiler/ppc/instruction-selector-ppc.cc
+++ b/src/compiler/ppc/instruction-selector-ppc.cc
@@ -971,6 +971,11 @@ void InstructionSelector::VisitRoundInt64ToFloat32(Node* node) {
 void InstructionSelector::VisitRoundInt64ToFloat64(Node* node) {
   VisitRR(this, kPPC_Int64ToDouble, node);
 }
+
+
+void InstructionSelector::VisitRoundUint64ToFloat64(Node* node) {
+  UNIMPLEMENTED();
+}
 #endif