[turbofan] Implemented the optional Float32RoundTiesEven operator.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index b7f78b888b471544b3951f857543e1d93637d66d..5114f458c15829374f5b931b44f401feb9c24be5 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -2307,6 +2307,12 @@ Type* Typer::Visitor::TypeFloat64RoundTiesAway(Node* node) {
 }
 
 
+Type* Typer::Visitor::TypeFloat32RoundTiesEven(Node* node) {
+  // TODO(sigurds): We could have a tighter bound here.
+  return Type::Number();
+}
+
+
 Type* Typer::Visitor::TypeFloat64RoundTiesEven(Node* node) {
   // TODO(sigurds): We could have a tighter bound here.
   return Type::Number();