[runtime] We don't need an actual instance type for JSIteratorResult.

src/objects-debug.cc

Index: src/objects-debug.cc
diff --git a/src/objects-debug.cc b/src/objects-debug.cc
index 9ae3048dd27cf4b6b4b7540d07e4bed166b9358c..b183c9c8e030b29ca734943e89281dd5430d3a65 100644
--- a/src/objects-debug.cc
+++ b/src/objects-debug.cc
@@ -150,9 +150,6 @@ void HeapObject::HeapObjectVerify() {
     case JS_MAP_ITERATOR_TYPE:
       JSMapIterator::cast(this)->JSMapIteratorVerify();
       break;
-    case JS_ITERATOR_RESULT_TYPE:
-      JSIteratorResult::cast(this)->JSIteratorResultVerify();
-      break;
     case JS_WEAK_MAP_TYPE:
       JSWeakMap::cast(this)->JSWeakMapVerify();
       break;
@@ -764,14 +761,6 @@ void JSMapIterator::JSMapIteratorVerify() {
 }
 
 
-void JSIteratorResult::JSIteratorResultVerify() {
-  CHECK(IsJSIteratorResult());
-  JSObjectVerify();
-  VerifyPointer(done());
-  VerifyPointer(value());
-}
-
-
 void JSWeakMap::JSWeakMapVerify() {
   CHECK(IsJSWeakMap());
   JSObjectVerify();