WPT: Adjust expected timing resolution

We recently increased[1] the minimum resolution of web-exposed timers.
This patch relaxes the WPT tests accordingly to allow for a higher
resolution (with a small delta to account for floating point errors).

Bug: 897775

[1] https://chromium-review.googlesource.com/c/1290916

Change-Id: I6f8a8d8ac2b827ae54718db6f8940cafb1cad665
Reviewed-on: https://chromium-review.googlesource.com/c/1298017Reviewed-by: Nicolás Peña Moreno <npm@chromium.org>
Commit-Queue: Sami Kyöstilä <skyostil@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603461}

third_party/WebKit/LayoutTests/TestExpectations

@@ -5687,8 +5687,6 @@ crbug.com/895777 external/wpt/infrastructure/assumptions/blank.html [ Failure Cr
 crbug.com/896765 [ Linux Mac Win ] http/tests/performance-timing/element-timing/observe-child-element.html [ Failure Pass ]
 
 #Sheriff 2018-10-22
-crbug.com/897775 [ Linux Mac Win ] external/wpt/performance-timeline/webtiming-resolution.any.html [ Failure Pass ]
-crbug.com/897775 [ Linux Mac Win ] external/wpt/performance-timeline/webtiming-resolution.any.worker.html [ Failure Pass ]
 crbug.com/897849 [ Mac10.13 Debug ] accessibility/element-role-mapping-normal.html [ Pass Timeout ]
 crbug.com/897849 [ Mac10.13 Debug ] accessibility/table-header-column-row.html [ Pass Timeout ]
 crbug.com/897075 [ Win10 ] inspector-protocol/css/css-coverage-new-stylesheet.js [ Failure Pass ]

third_party/WebKit/LayoutTests/external/wpt/performance-timeline/webtiming-resolution.any.js

@@ -5,8 +5,9 @@ function testTimeResolution(highResTimeFunc, funcString) {
         while (t0 == t1) {
             t1 = highResTimeFunc();
         }
-        assert_greater_than_equal(t1 - t0, 0.02, 'The second ' + funcString + ' should be much greater than the first');
-    }, 'Verifies the resolution of ' + funcString + ' is at least 20 microseconds.');
+        const epsilon = 1e-5;
+        assert_greater_than_equal(t1 - t0, 0.005 - epsilon, 'The second ' + funcString + ' should be much greater than the first');
+    }, 'Verifies the resolution of ' + funcString + ' is at least 5 microseconds.');
 }
 
 function timeByPerformanceNow() {