harness test: tcoHelper.js

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>

test/harness/tcoHelper.js

+// Copyright (c) 2017 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: >
+    Including tcoHelper.js will expose:
+
+        var $MAX_ITERATIONS = 100000;
+
+    This defines the number of consecutive recursive function calls that must be
+    made in order to prove that stack frames are properly destroyed according to
+    ES2015 tail call optimization semantics.
+
+includes: [tcoHelper.js]
+---*/
+
+
+assert.sameValue($MAX_ITERATIONS, 100000);