Bug 1501619 [wpt PR 13698] - [run_web_tests] Check for extra baselines, a=testonly

Automatic update from web-platform-tests[run_web_tests] Check for extra baselines

After https://chromium-review.googlesource.com/c/chromium/src/+/1277654,
we no longer generate text result of many tests, thus these tests no
longer need the text baselines.

This CL checks for extra baselines in the following cases:
1. Extra -expected.png (existing logic) for ref tests;
2. Extra -expected.txt, -expected.png, -expected.wav if the test doesn't
   generate the result;
3. Extra -expected.txt for all-pass testharness tests.

For 2, the extra baseline will be treated as a mismatch failure (which
can be interpreted as that the test doesn't generate the result, but
the baseline expects the result).

For 1 and 3, there are just warning messages because for now we don't
have a good way to present them in the layout test result page.

We have already had a similar logic in pre-submit for 3 and the new
check in run_web_tests is more accurate. For other types of extra
baselines, it's hard to implement the check in presubmit because it
needs more knowledge than static pre-submit knows.

Bug: 703899
Cq-Include-Trybots: luci.chromium.try​:linux-blink-gen-property-trees;luci.chromium.try​:linux_layout_tests_layout_ng;luci.chromium.try​:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I9016d5583791f179f1d51561245602af615d21de
Reviewed-on: https://chromium-review.googlesource.com/c/1286894
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#602378}

--

wpt-commits: 07d9f452d740d98ded5b11c176ba783fe9d80e5b
wpt-pr: 13698


--HG--
rename : testing/web-platform/tests/webaudio/the-audio-api/the-audiobuffersourcenode-interface/audiobuffersource-multi-channels-expected.wav => testing/web-platform/tests/webaudio/the-audio-api/the-audiobuffersourcenode-interface/resources/audiobuffersource-multi-channels-expected.wav

testing/web-platform/tests/webaudio/the-audio-api/the-audiobuffersourcenode-interface/audiobuffersource-multi-channels.html

@@ -28,7 +28,7 @@ Test AudioBufferSourceNode supports 5.1 channel.
         }, 'Creating context for testing').notThrow();
         should(
           Audit
-            .loadFileFromUrl('audiobuffersource-multi-channels-expected.wav')
+            .loadFileFromUrl('resources/audiobuffersource-multi-channels-expected.wav')
             .then(arrayBuffer => {
               context.decodeAudioData(arrayBuffer).then(audioBuffer => {
                 expectedAudio = audioBuffer;