Gardening: Temporarily mark another CSP WPT as flaky.

r553437 added one for dedicated-inheritance.html, but shared is also
flaky:
external/wpt/content-security-policy/inside-worker/shared-inheritance.html

Bug: 836627
Change-Id: I84be5f95c0b1a2aa267ed76c849bb98f4b4b5dcd
TBR: robertma
NOTRY: true
Reviewed-on: https://chromium-review.googlesource.com/1027213
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553475}

third_party/WebKit/LayoutTests/TestExpectations

@@ -2306,6 +2306,7 @@ crbug.com/836377 external/wpt/service-workers/service-worker/worker-interception
 crbug.com/836377 virtual/outofblink-cors/external/wpt/service-workers/service-worker/worker-interception-redirect.https.html [ Timeout ]
 
 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 ]
 
 # ====== New tests from wpt-importer added here ======
 crbug.com/626703 external/wpt/css/css-contain/counter-scoping-002.html [ Failure ]