Bug 1632604 [wpt PR 23210] - Increase timeout for wpt...CSS2...line-height-interpolation.html, a=testonly

Automatic update from web-platform-tests
Increase timeout for wpt...CSS2...line-height-interpolation.html

This test was running with an average speed close to its timeout and
was occasionally exceeding it, causing flakes. Marking it as slow as
per wpt guidelines.

Bug: 1073460
Change-Id: I2028d64ed727242ec3873c5172a08ecebbc45a73
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2163395
Commit-Queue: George Steel <gtsteel@chromium.org>
Reviewed-by: Kevin Ellis <kevers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#762061}

--

wpt-commits: e4040c2f7748ba77d996fc85e51499fadfd63eda
wpt-pr: 23210

testing/web-platform/tests/css/CSS2/linebox/animations/line-height-interpolation.html

@@ -3,6 +3,7 @@
 <title>line-height interpolation</title>
 <link rel="help" href="https://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">
 <meta name="assert" content="line-height supports animation by computation">
+<meta name="timeout" content="long">
 
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>