Reenable fast/speech/script/start-multiple.html

The test was rewritten in https://crrev.com/c/1111910 and now uses a mock
speech recognizer written in js. The previous mock recognizer was removed
and the test was using the actual speech recognition service.

Bug: 855873
Change-Id: I89a902092ee26c16f3624bd359c0cbf55b74e1d8
Tbr: shend@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/1117620Reviewed-by: Adithya Srinivasan <adithyas@chromium.org>
Commit-Queue: Adithya Srinivasan <adithyas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#570908}

third_party/WebKit/LayoutTests/TestExpectations

@@ -4713,7 +4713,6 @@ crbug.com/855222 [ Mac ] external/wpt/magnetometer/Magnetometer-iframe-access.ht
 crbug.com/855055 [ Mac ] virtual/threaded/animations/interpolation/svg-stroke-dasharray-interpolation.html [ Pass Timeout ]
 
 # Sheriff 2018-06-25
-crbug.com/855873 [ Mac Win7 ] fast/speech/scripted/start-multiple.html [ Pass Crash ]
 crbug.com/855860 [ Linux ] virtual/outofblink-cors/http/tests/fetch/serviceworker-proxied/thorough/redirect-password-base-https-other-https.html [ Pass Timeout ]
 crbug.com/855816 [ Win7 ] virtual/stable/http/tests/navigation/rename-subframe-goback.html [ Pass Timeout ]
 crbug.com/856330 external/wpt/service-workers/service-worker/about-blank-replacement.https.html [ Pass Timeout ]