[turbofan] Added the optional Float64RoundTiesEven operator to turbofan.

src/compiler/x87/instruction-selector-x87.cc

Index: src/compiler/x87/instruction-selector-x87.cc
diff --git a/src/compiler/x87/instruction-selector-x87.cc b/src/compiler/x87/instruction-selector-x87.cc
index 3a0335b55b4fd8fe5edce4e8d13afa8870910261..af3889228a64ba432f708b3645ac81cccea80293 100644
--- a/src/compiler/x87/instruction-selector-x87.cc
+++ b/src/compiler/x87/instruction-selector-x87.cc
@@ -864,6 +864,11 @@ void InstructionSelector::VisitFloat64RoundTiesAway(Node* node) {
 }
 
 
+void InstructionSelector::VisitFloat64RoundTiesEven(Node* node) {
+  UNREACHABLE();
+}
+
+
 void InstructionSelector::EmitPrepareArguments(NodeVector* arguments,
                                                const CallDescriptor* descriptor,
                                                Node* node) {