Make fetch-event.https.html faster.

It was registering a service worker for each test case, and had a lot
of test cases.

This changes the file to register a single service worker at the
beginning, and unregister it at the end.

Bug: 847787
Change-Id: Ic2536824a3c57e86bb5e042287e9e62e6222ad9a
Reviewed-on: https://chromium-review.googlesource.com/1087188Reviewed-by: Makoto Shimazu <shimazu@chromium.org>
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564770}

third_party/WebKit/LayoutTests/TestExpectations

@@ -1895,8 +1895,6 @@ crbug.com/771118 virtual/service-worker-servicification/external/wpt/service-wor
 
 crbug.com/846237 virtual/service-worker-servicification/external/wpt/service-workers/service-worker/import-scripts-updated-flag.https.html [ Crash ]
 
-crbug.com/847565 [ Mac Linux ] virtual/service-worker-servicification/external/wpt/service-workers/service-worker/fetch-event.https.html [ Pass Timeout ]
-
 crbug.com/492664 [ Linux ] external/wpt/css/css-writing-modes/box-offsets-rel-pos-vlr-005.xht [ Failure ]
 crbug.com/492664 [ Linux ] external/wpt/css/css-writing-modes/box-offsets-rel-pos-vrl-004.xht [ Failure ]
 crbug.com/492664 [ Mac ] external/wpt/css/css-writing-modes/bidi-embed-002.html [ Failure ]
@@ -4828,7 +4826,6 @@ crbug.com/841567 fast/scrolling/scrollbar-tickmarks-hittest.html [ Failure Pass
 
 # Flakes 2018-06-04
 crbug.com/847870 fast/webgl/texImage-imageBitmap-from-canvas-resize.html [ Timeout Pass ]
-crbug.com/847787 external/wpt/service-workers/service-worker/fetch-event.https.html [ Timeout Pass ]
 crbug.com/847697 virtual/video-surface-layer/media/controls/overflow-menu-always-visible.html [ Pass Failure ]
 crbug.com/849256 [ Mac ] virtual/gpu-rasterization/images/color-profile-iframe.html [ Pass Failure ]
 crbug.com/849258 [ Mac ] virtual/gpu-rasterization/images/imagemap-focus-ring-outline-color.html [ Pass Failure ]

third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/fetch-event.https-expected.txt

 This is a testharness.js-based test.
+PASS global setup
 PASS Service Worker headers in the request of a fetch event
 PASS Service Worker responds to fetch event with string
 PASS Service Worker responds to fetch event using request fragment with string
@@ -15,7 +16,7 @@ PASS Service Worker event.respondWith must set the used flag
 PASS Service Worker should expose FetchEvent URL fragments.
 PASS Service Worker responds to fetch event with the correct cache types
 PASS Service Worker should intercept EventSource
-FAIL Service Worker responds to fetch event with the correct integrity_metadata assert_unreached: unexpected rejection: assert_equals: integrity expected "gs0nqru8KbsrIt5YToQqS9fYao4GQJXtcId610g7cCU=" but got "" Reached unreachable code
+FAIL Service Worker responds to fetch event with the correct integrity_metadata assert_equals: integrity expected "gs0nqru8KbsrIt5YToQqS9fYao4GQJXtcId610g7cCU=" but got ""
 PASS FetchEvent#body is a string
 PASS FetchEvent#body is a string and is passed to network fallback
 PASS FetchEvent#body is a blob
@@ -32,5 +33,6 @@ FAIL FetchEvent#request.isHistoryNavigation is false (with location.reload) asse
 FAIL FetchEvent#request.isHistoryNavigation is true (with history.go(-2)) assert_equals: expected "method = GET, isHistoryNavigation = false" but got "method = GET, isHistoryNavigation = undefined"
 FAIL FetchEvent#request.isHistoryNavigation is true (with history.go(2)) assert_equals: expected "method = GET, isHistoryNavigation = false" but got "method = GET, isHistoryNavigation = undefined"
 FAIL FetchEvent#request.isHistoryNavigation is true (POST + history.go(-1)) assert_equals: expected "method = GET, isHistoryNavigation = false" but got "method = GET, isHistoryNavigation = undefined"
+PASS restore global state
 Harness: the test ran to completion.