Add LayoutTest for PerformanceObserver inside Worker

third_party/WebKit/LayoutTests/TestExpectations

 # This is the main failure suppression file for Blink LayoutTests.
 # Further documentation:
 # https://chromium.googlesource.com/chromium/src/+/master/docs/testing/layout_test_expectations.md
 
 # Intentional failures to test the layout test system.
 Bug(intentional) harness-tests/crash.html [ Crash ]
 Bug(intentional) harness-tests/timeout.html [ Timeout ]
 
 # ====== Oilpan-only failures from here ======
 # Most of these actually cause the tests to report success, rather than
@@ skipping 2858 matching lines @@
 
 # Failures when using libc++.  Rebaseline after landing https://codereview.chromium.org/2933573002/
 crbug.com/734873 [ Linux ] fast/backgrounds/size/contain-and-cover.html [ Pass Failure ]
 
 # Compositor worker tests are flaky, crashing and timing out
 crbug.com/727505 [ Linux Mac Win ] virtual/threaded/fast/compositorworker/basic-plumbing-main-to-worker.html [ Pass Failure Timeout Crash ]
 crbug.com/727505 [ Linux Mac Win ] virtual/threaded/fast/compositorworker/request-animation-frame.html [ Pass Failure Timeout Crash ]
 crbug.com/727991 [ Linux Mac Win ] virtual/threaded/fast/compositorworker/visual-update.html [ Pass Failure Timeout Crash ]
 
 crbug.com/729836 [ Win ] fast/workers/worker-document-leak.html [ Pass Failure ]
+crbug.com/705820 fast/workers/worker-with-performance-observer.html [ Failure ]

[falken, 2017/07/04 14:46:35]

Why add a test that's failing? Instead of a Failure line here, it should have a
-expected.txt file instead.

[npm, 2017/07/05 21:53:53]

Because this is actually not working. We will enable once the bug referenced is
fixed.

[falken, 2017/07/05 23:30:08]

I can't find where this is documented now, but it's recommended practice to use
an -expected.txt file instead of [ Failure ] even if the expected test output is
not ultimately what's "correct". It allows us to catch unexpected regressions in
test output. I.e., we basically should never have [ Failure ] lines unless the
test is flakily failing in different ways.

 
 # Sensor tests fail on Mac swarming
 crbug.com/731018 [ Mac ] sensor/accelerometer.html [ Failure Pass Crash ]
 crbug.com/731018 [ Mac ] sensor/ambient-light-sensor.html [ Failure Pass Crash ]
 crbug.com/731018 [ Mac ] sensor/gyroscope.html [ Failure Pass Crash ]
 crbug.com/731018 [ Mac ] sensor/magnetometer.html [ Failure Pass Crash ]
 crbug.com/731018 [ Mac ] sensor/orientation-sensor.html [ Failure Pass Crash ]
 
 # More flaky tests on Mac
 crbug.com/731111 [ Mac ] http/tests/media/progress-events-generated-correctly.html [ Failure Pass Timeout ]
@@ skipping 92 matching lines @@
 crbug.com/736177 [ Mac ] virtual/layout_ng/fast/block/basic/001.html [ Failure Pass ]
 crbug.com/736177 [ Mac ] virtual/mojo-loading/http/tests/misc/acid2-pixel.html [ Failure Pass ]
 crbug.com/736177 [ Mac ] virtual/off-main-thread-fetch/http/tests/misc/acid2-pixel.html [ Failure Pass ]
 crbug.com/736177 [ Mac ] virtual/prefer_compositing_to_lcd_text/scrollbars/custom-scrollbar-with-incomplete-style.html [ Failure Pass ]
 crbug.com/736177 [ Mac ] virtual/rootlayerscrolls/scrollbars/custom-scrollbar-with-incomplete-style.html [ Failure Pass ]
 
 crbug.com/734762 [ Mac Debug ] inspector-protocol/timeline/page-frames.js [ Failure ]
 
 crbug.com/736255 [ Mac ] external/wpt/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-baseline-multi-item-vert-001b.html [ Skip ]
 crbug.com/736732 virtual/enable_wasm/external/wpt/wasm/wasm_local_iframe_test.html [ Timeout Pass ]