Bug 1526647 [wpt PR 15270] - Relax required SNR a bit, a=testonly

Automatic update from web-platform-tests
Relax required SNR a bit

The required SNR was a little too high for some Mac OS bots.  Make it
a little smaller.

Bug: 929435
Change-Id: I5fbfe6573f4907f33999085e52bb22f4b4b9a126
Reviewed-on: https://chromium-review.googlesource.com/c/1457228
Commit-Queue: Raymond Toy <rtoy@chromium.org>
Reviewed-by: Hongchan Choi <hongchan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#631309}

--

wpt-commits: 91d81bb73d5e8424e45918c84e275a9d46c51d51
wpt-pr: 15270

testing/web-platform/tests/webaudio/the-audio-api/the-audiobuffersourcenode-interface/sub-sample-buffer-stitching.html

@@ -26,7 +26,7 @@
             // Experimentally determined thresholds.  DO NOT relax these values
             // to far from these values to make the tests pass.
             const errorThreshold = 9.0957e-5;
-            const snrThreshold = 85.586;
+            const snrThreshold = 85.580;
 
             // Informative message
             should(sampleRate, 'Test 1: context.sampleRate')