Add tests for %TypedArray%.prototype.sort stability

tc39/ecma262#1433

test/built-ins/TypedArray/stability.js

@@ -0,0 +1,22 @@
+// Copyright (C) 2019 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.sort
+description: Stability of %TypedArray%.prototype.sort.
+info: |
+  https://github.com/tc39/ecma262/pull/1433
+includes: [testTypedArray.js, compareArray.js]
+features: [TypedArray]
+---*/
+
+// Treat 0..3, 4..7, etc. as equal.
+const compare = (a, b) => (a / 4 | 0) - (b / 4 | 0);
+
+testWithTypedArrayConstructors((TA) => {
+  const array = Array.from({ length: 128 }, (_, i) => i);
+  const typedArray = new TA(array);
+  assert(compareArray(
+    typedArray.sort(compare),
+    [0,1,2,3,4,5,6,7,9,8,10,11,14,13,12,15,127,126,125,124,123,122,121,120,119,118,117,116,115,114,113,112,111,110,109,108,107,106,105,104,103,102,101,100,99,98,97,96,95,94,93,92,91,90,89,88,87,86,85,84,83,82,81,80,79,78,77,76,75,74,73,72,71,70,69,68,67,66,65,64,63,62,61,60,59,58,57,56,55,54,53,52,51,50,49,48,47,46,45,44,43,42,41,40,39,38,37,36,35,34,33,32,31,30,29,28,27,26,25,24,23,22,21,20,19,18,17,16]
+  ), 'sort is stable');
+});