Increase timeout for flaking interpolation tests

The updated tests run a fair number of interpolations and push the
boundary of what should be characterized as a long test. Flakes are
typically clustered and the result of variability in speed of the
testing infrastructure and not indicative of true changes in
performance.

Bug: 1093451, 1092177, 1092141
Change-Id: Ia438ae758470e3e7eb695e59e1698734e6526c97
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2341804Reviewed-by: Xida Chen <xidachen@chromium.org>
Commit-Queue: Kevin Ellis <kevers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795956}

third_party/blink/web_tests/external/wpt/css/css-transforms/animation/transform-interpolation-001.html

@@ -3,6 +3,7 @@
 <title>transform interpolation</title>
 <link rel="help" href="https://drafts.csswg.org/css-transforms/#transform-property">
 <meta name="assert" content="transform supports animation as a transform list">
+<meta name="timeout" content="long">
 
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>

third_party/blink/web_tests/external/wpt/css/css-transforms/animation/transform-interpolation-005.html

@@ -3,7 +3,7 @@
 <title>transform interpolation</title>
 <link rel="help" href="https://drafts.csswg.org/css-transforms/#transform-property">
 <meta name="assert" content="transform supports animation as a transform list">
-
+<meta name="timeout" content="long">
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <script src="/css/support/interpolation-testcommon.js"></script>

third_party/blink/web_tests/external/wpt/css/css-transforms/animation/translate-interpolation.html

@@ -5,6 +5,7 @@
     <title>translate interpolation</title>
     <link rel="help" href="https://drafts.csswg.org/css-transforms-2/#propdef-translate">
     <meta name="assert" content="translate supports <length> and <percentage> animation.">
+    <meta name="timeout" content="long">
     <script src="/resources/testharness.js"></script>
     <script src="/resources/testharnessreport.js"></script>
     <script src="/css/support/interpolation-testcommon.js"></script>