LibJS: Convert StringIterator::create() to NonnullGCPtr

Userland/Libraries/LibJS/Runtime/StringIterator.cpp

@@ -10,9 +10,9 @@
 
 namespace JS {
 
-StringIterator* StringIterator::create(Realm& realm, DeprecatedString string)
+NonnullGCPtr<StringIterator> StringIterator::create(Realm& realm, DeprecatedString string)
 {
-    return realm.heap().allocate<StringIterator>(realm, move(string), *realm.intrinsics().string_iterator_prototype());
+    return *realm.heap().allocate<StringIterator>(realm, move(string), *realm.intrinsics().string_iterator_prototype());
 }
 
 StringIterator::StringIterator(DeprecatedString string, Object& prototype)

Userland/Libraries/LibJS/Runtime/StringIterator.h

@@ -15,7 +15,7 @@ class StringIterator final : public Object {
     JS_OBJECT(StringIterator, Object);
 
 public:
-    static StringIterator* create(Realm&, DeprecatedString string);
+    static NonnullGCPtr<StringIterator> create(Realm&, DeprecatedString string);
 
     virtual ~StringIterator() override = default;