[turbofan] Add the RoundInt32ToFloat32 operator to turbofan.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index c1f816d34bc451a624acf38594fa1b6d1908bbbd..2829d6c55eac08d7048e60a08bc65ceece3aea52 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -2200,6 +2200,11 @@ Type* Typer::Visitor::TypeTruncateInt64ToInt32(Node* node) {
 }
 
 
+Type* Typer::Visitor::TypeRoundInt32ToFloat32(Node* node) {
+  return Type::Intersect(Type::PlainNumber(), Type::UntaggedFloat32(), zone());
+}
+
+
 Type* Typer::Visitor::TypeRoundInt64ToFloat32(Node* node) {
   return Type::Intersect(Type::PlainNumber(), Type::UntaggedFloat32(), zone());
 }