Add Catch Finally Functions test

test/built-ins/Promise/prototype/finally/rejected-observable-then-calls-argument.js

@@ -0,0 +1,28 @@
+// Copyright (C) 2019 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-catchfinallyfunctions
+description: >
+  thrower is anonymous built-in function with length of 1 that throws reason.
+info: |
+  Catch Finally Functions
+
+  ...
+  8. Let thrower be equivalent to a function that throws reason.
+  9. Return ? Invoke(promise, "then", « thrower »).
+
+  The "length" property of a Catch Finally function is 1.
+features: [Promise.prototype.finally, Reflect.construct]
+includes: [isConstructor.js]
+flags: [async]
+---*/
+
+Promise.reject(new Test262Error()).finally(function() {});
+Promise.prototype.then = function(thrower) {
+  assert(!isConstructor(thrower));
+  assert.sameValue(thrower.length, 1);
+  assert.sameValue(thrower.name, '');
+  assert.throws(Test262Error, thrower);
+
+  $DONE();
+};