[WIP] JSForInLowering and JSForInHasOwnProperty.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index 1055e11d3fb7c37682b63c06fdef0b808f58b505..192b8bcac69b9934e61218384fb1ed96acb78280 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -1651,9 +1651,16 @@ Type* Typer::Visitor::TypeJSConvertReceiver(Node* node) {
   return Type::Receiver();
 }
 
+Type* Typer::Visitor::TypeJSForInHasOwnProperty(Node* node) {
+  return Type::Boolean();
+}
+
+Type* Typer::Visitor::TypeJSForInLoadProperty(Node* node) {
+  return Type::NonInternal();
+}
 
 Type* Typer::Visitor::TypeJSForInNext(Node* node) {
-  return Type::Union(Type::String(), Type::Undefined(), zone());
+  return Type::StringOrUndefined();
 }
 
 
@@ -1878,6 +1885,10 @@ Type* Typer::Visitor::TypeConvertTaggedHoleToUndefined(Node* node) {
 
 Type* Typer::Visitor::TypeAllocate(Node* node) { return Type::Any(); }
 
+Type* Typer::Visitor::TypeLoadFieldByIndex(Node* node) {
+  return Type::NonInternal();
+}
+
 Type* Typer::Visitor::TypeLoadField(Node* node) {
   return FieldAccessOf(node->op()).type;
 }