[turbofan] Implemented the optional Float32RoundTiesEven operator.

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

Index: src/compiler/mips/instruction-selector-mips.cc
diff --git a/src/compiler/mips/instruction-selector-mips.cc b/src/compiler/mips/instruction-selector-mips.cc
index b6785e32976c95034bf65e64d63b35366253cdef..0877e0005e4bf7a9a16196cbe11ddfc762df0f89 100644
--- a/src/compiler/mips/instruction-selector-mips.cc
+++ b/src/compiler/mips/instruction-selector-mips.cc
@@ -678,6 +678,11 @@ void InstructionSelector::VisitFloat64RoundTiesAway(Node* node) {
 }
 
 
+void InstructionSelector::VisitFloat32RoundTiesEven(Node* node) {
+  UNREACHABLE();
+}
+
+
 void InstructionSelector::VisitFloat64RoundTiesEven(Node* node) {
   VisitRR(this, kMipsFloat64RoundTiesEven, node);
 }