LibJS: Convert Date::create() to NonnullGCPtr

Userland/Libraries/LibJS/Runtime/Date.cpp

@@ -21,9 +21,9 @@ static Crypto::SignedBigInteger const s_one_billion_bigint { 1'000'000'000 };
 static Crypto::SignedBigInteger const s_one_million_bigint { 1'000'000 };
 static Crypto::SignedBigInteger const s_one_thousand_bigint { 1'000 };
 
-Date* Date::create(Realm& realm, double date_value)
+NonnullGCPtr<Date> Date::create(Realm& realm, double date_value)
 {
-    return realm.heap().allocate<Date>(realm, date_value, *realm.intrinsics().date_prototype());
+    return *realm.heap().allocate<Date>(realm, date_value, *realm.intrinsics().date_prototype());
 }
 
 Date::Date(double date_value, Object& prototype)

Userland/Libraries/LibJS/Runtime/Date.h

@@ -15,8 +15,7 @@ class Date final : public Object {
     JS_OBJECT(Date, Object);
 
 public:
-    static Date* create(Realm&, double date_value);
-    static Date* now(VM&);
+    static NonnullGCPtr<Date> create(Realm&, double date_value);
 
     virtual ~Date() override = default;