Disable fast/dom/css-delete-doc.html on linux-rel

No-try: true
Tbr: masonfreed@chromium.org
Bug: 1135978
Change-Id: Ic03a6fc8a95668d93bc6316cf296f786cf0b365d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2457946Reviewed-by: Ella Ge <eirage@chromium.org>
Commit-Queue: Ella Ge <eirage@chromium.org>
Cr-Commit-Position: refs/heads/master@{#814778}

third_party/blink/web_tests/TestExpectations

@@ -6617,3 +6617,4 @@ crbug.com/1133821 virtual/off-main-thread-css-paint/external/wpt/css/css-paint-a
 
 #Sheriff 2020-10-07
 crbug.com/1135405 http/tests/devtools/sources/debugger-pause/debugger-pause-infinite-loop.js [ Pass Timeout ]
+crbug.com/1135978 [ Linux Release ] fast/dom/css-delete-doc.html [ Pass Timeout ]