Add Float64Round operator.

src/compiler/x64/instruction-selector-x64.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/generic-node-inl.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 1091 matching lines @@
   FlagsContinuation cont(kUnorderedLessThan, node);
   VisitFloat64Compare(this, node, &cont);
 }
 
 
 void InstructionSelector::VisitFloat64LessThanOrEqual(Node* node) {
   FlagsContinuation cont(kUnorderedLessThanOrEqual, node);
   VisitFloat64Compare(this, node, &cont);
 }
 
+
+// static
+MachineOperatorBuilder::Flags InstructionSelector::GetSupportedOperators() {
+  return MachineOperatorBuilder::kNoFlags;
+}
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8