bluetooth: Update BluetoothDevice IDL tests

These tests were not functioning correctly because `assert_throws` was
not being passed an Error.  Furthermore, the use of the `expected.txt`
file is brittle since it includes a warning output with a line number.

BUG=769404

Change-Id: Ie867e6b99fc87d7c9b8b7259684f2ddd3cdc37a2
Reviewed-on: https://chromium-review.googlesource.com/688295Reviewed-by: Vincent Scheib <scheib@chromium.org>
Commit-Queue: Conley Owens <cco3@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505429}

third_party/WebKit/LayoutTests/bluetooth/idl/idl-BluetoothDevice.html

@@ -5,27 +5,27 @@
 <script src="../../resources/bluetooth/web-bluetooth-test.js"></script>
 <script src="../../resources/mojo-helpers.js"></script>
 <script>
+'use strict';
+const test_desc_idl = 'BluetoothDevice IDL test.';
 test(() => {
-  assert_throws(null, () => new BluetoothDevice(),
-                'the constructor should not be callable with "new"');
-  assert_throws(null, () => BluetoothDevice(),
-                'the constructor should not be callable');
-}, 'BluetoothDevice IDL test');
+  assert_throws(new TypeError(), () => new BluetoothDevice(),
+      'the constructor should not be callable with "new"');
+  assert_throws(new TypeError(), () => BluetoothDevice(),
+      'the constructor should not be callable');
+}, test_desc_idl);
 
-promise_test(() => {
-  return setUpHealthThermometerAndHeartRateDevices()
-    .then(() => requestDeviceWithKeyDown({
-      filters: [{services: ['heart_rate']}]}))
-    .then(device => {
-      assert_equals(device.constructor.name, 'BluetoothDevice');
-
-      // Attempt (and fail) to overwrite all members, verifying they are
-      // readonly.
-      var old_device_id = device.id;
-      device.id = 'overwritten';
-      device.name = 'overwritten';
-      assert_equals(device.id, old_device_id);
-      assert_equals(device.name, 'Heart Rate');
-    });
-}, 'BluetoothDevice attributes.');
+const test_desc_attr = 'BluetoothDevice attributes.';
+let device;
+promise_test(() => getHealthThermometerDevice()
+  .then(_ => ({device} = _))
+  .then(() => {
+    assert_equals(device.constructor.name, 'BluetoothDevice');
+    var old_device_id = device.id;
+    assert_throws(new TypeError(), () => device.id = 'overwritten',
+      'the device id should not be writable');
+    assert_throws(new TypeError(), () => device.name = 'overwritten',
+      'the device name should not be writable');
+    assert_equals(device.id, old_device_id);
+    assert_equals(device.name, 'Health Thermometer');
+  }),  test_desc_attr);
 </script>

third_party/WebKit/LayoutTests/platform/mac/bluetooth/idl/idl-BluetoothDevice-expected.txt

-This is a testharness.js-based test.
-FAIL BluetoothDevice IDL test Test bug: need to pass exception to assert_throws()
-PASS BluetoothDevice attributes.
-Harness: the test ran to completion.
-

third_party/WebKit/LayoutTests/platform/win/bluetooth/idl/idl-BluetoothDevice-expected.txt

-CONSOLE MESSAGE: line 169: Web Bluetooth is experimental on this platform. See https://github.com/WebBluetoothCG/web-bluetooth/blob/gh-pages/implementation-status.md
-This is a testharness.js-based test.
-FAIL BluetoothDevice IDL test Test bug: need to pass exception to assert_throws()
-PASS BluetoothDevice attributes.
-Harness: the test ran to completion.
-