Mark inside-worker/dedicated-script-expected.txt flaky

Tbr: robertma
Bug: 836627
Change-Id: I956f30dcc13087ee16a655102d8bbd706dab296e
Reviewed-on: https://chromium-review.googlesource.com/1029953
Commit-Queue: Max Morin <maxmorin@chromium.org>
Reviewed-by: Max Morin <maxmorin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553972}

third_party/WebKit/LayoutTests/TestExpectations

@@ -2300,6 +2300,7 @@ crbug.com/832071 virtual/navigation-mojo-response/external/wpt/service-workers/s
 crbug.com/833215 [ Mac10.12 Mac10.13 Retina ] external/wpt/accelerometer/Accelerometer.https.html [ Pass Timeout ]
 crbug.com/833215 [ Linux ] external/wpt/accelerometer/Accelerometer.https.html [ Pass Failure ]
 
+crbug.com/836627 external/wpt/content-security-policy/inside-worker/dedicated-script.html [ Pass Failure ]
 crbug.com/836627 external/wpt/content-security-policy/inside-worker/dedicated-inheritance.html [ Pass Failure ]
 crbug.com/836627 external/wpt/content-security-policy/inside-worker/shared-inheritance.html [ Pass Failure ]