TypedArray.prototype.sort: check result of compareFn is immediately converted ToNumber (#1694)

test/built-ins/TypedArray/prototype/sort/sort-tonumber.js

+// Copyright (C) 2018 Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.sort
+description: The result of compareFn is immediately passed through ToNumber
+info: |
+  22.2.3.26 %TypedArray%.prototype.sort ( comparefn )
+
+  ...
+  2. If comparefn is not undefined, then
+    a. Let v be ? ToNumber(? Call(comparefn, undefined, « x, y »)).
+    b. If IsDetachedBuffer(buffer) is true, throw a TypeError exception.
+    ...
+  ...
+includes: [testTypedArray.js, detachArrayBuffer.js]
+features: [TypedArray]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  var ta = new TA(4);
+  var ab = ta.buffer;
+
+  var called = false;
+  assert.throws(TypeError, function() {
+    ta.sort(function(a, b) {
+      // IsDetachedBuffer is checked right after calling comparefn.
+      // So, detach the ArrayBuffer to cause sort to throw, to make sure we're actually calling ToNumber immediately (as spec'd)
+      // (a possible bug is to wait until the result is inspected to call ToNumber, rather than immediately)
+      $DETACHBUFFER(ab);
+      return {
+        [Symbol.toPrimitive]() { called = true; }
+      };
+    });
+  });
+
+  assert.sameValue(true, called);
+});