[turbofan] Add PlainPrimitiveToNumber simplified operator.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index 88a3666565875f8a8715326b3a1577bc8ada348a..24e93e1adad702bf6603afc1e371c47d39b1e39c 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -1462,7 +1462,7 @@ Bounds Typer::Visitor::TypeBooleanNot(Node* node) {
 
 
 Bounds Typer::Visitor::TypeBooleanToNumber(Node* node) {
-  return Bounds(Type::None(zone()), typer_->zero_or_one);
+  return TypeUnaryOp(node, ToNumber);
 }
 
 
@@ -1516,6 +1516,11 @@ Bounds Typer::Visitor::TypeNumberToUint32(Node* node) {
 }
 
 
+Bounds Typer::Visitor::TypePlainPrimitiveToNumber(Node* node) {
+  return TypeUnaryOp(node, ToNumber);
+}
+
+
 Bounds Typer::Visitor::TypeReferenceEqual(Node* node) {
   return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }