BigInt: BigInt .toString() returns only decimal digits, does not include BigIntLiteralSuffix

test/built-ins/BigInt/prototype/toString/string-is-code-units-of-decimal-digits-only.js

+// Copyright 2017 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-tostring-applied-to-the-bigint-type
+description: BigInt .toString() returns only decimal digits, does not include BigIntLiteralSuffix
+info: |
+
+  ToString Applied to the BigInt Type
+
+    The abstract operation ToString converts a BigInt i to String format as follows:
+
+    ...
+    Return the String consisting of the code units of the digits of the decimal representation of i.
+
+features: [BigInt]
+---*/
+
+assert.sameValue(BigInt(0).toString(), "0", "BigInt(0).toString() === '0'");
+assert.sameValue(BigInt(0n).toString(), "0", "BigInt(0n).toString() === '0'");
+assert.sameValue(0n.toString(), "0", "0n.toString() === '0'");