Bug 1589385 [wpt PR 19759] - Make interpolation-testcommon.js produce consistent subtest names, a=testonly

Automatic update from web-platform-tests
Make interpolation-testcommon.js produce consistent subtest names (#19759)

Passing expectations.expect through computed style may mutate it in an
implementation-dependent way. Those are interop bugs when that happens,
but we shouldn't surface it in the subtest name as that causes it to
fluctuate between browsers and releases.
--

wpt-commits: 4e9c00e23f9b786eb7f2927cd501714c98196e4d
wpt-pr: 19759

testing/web-platform/tests/css/support/interpolation-testcommon.js

@@ -284,7 +284,7 @@
           comparisonFunction(
               getComputedStyle(target).getPropertyValue(property),
               expectedValue);
-        }, `${testText} at (${expectation.at}) should be [${sanitizeUrls(expectedValue)}]`);
+        }, `${testText} at (${expectation.at}) should be [${sanitizeUrls(expectation.expect)}]`);
       };
       return target;
     });