AggregateError: update args order evaluation (#2647)

Fixes #2646

test/built-ins/NativeErrors/AggregateError/order-of-args-evaluation.js

@@ -0,0 +1,41 @@
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-aggregate-error
+description: >
+  Process arguments in superclass-then-subclass order
+info: |
+  AggregateError ( errors, message )
+
+  TODO: get updated prose
+
+features: [AggregateError, Symbol.iterator]
+includes: [promiseHelper.js]
+---*/
+
+let sequence = [];
+const message = {
+  toString() {
+    sequence.push(1);
+    return '';
+  }
+};
+const errors = {
+  [Symbol.iterator]() {
+    sequence.push(2);
+    return {
+      next() {
+        sequence.push(3);
+        return {
+          done: true
+        };
+      }
+    };
+  }
+};
+
+new AggregateError(errors, message);
+
+assert.sameValue(sequence.length, 3);
+checkSequence(sequence);