Add test expectations for web_tests.

They are all failing because of https://crbug.com/991194. A document is
frozen. When the back-forward-cache is enabled, it blocks JavaScript and
evict the document. The problem is that it applies to every frozen
documents, even the ones not in the BackForwardCache.

Bug: 992325, 991194
Change-Id: I8239dcfab079630e192fa433c7a7e456a43ccaf5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1746247Reviewed-by: Arthur Hemery <ahemery@chromium.org>
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#685522}

third_party/blink/web_tests/FlagExpectations/enable-features=BackForwardCache

+# These tests currently fail when run with --enable-features=BackForwardCache
+
+# Document are deleted, because they execute javascript in a frozen document.
+# This shouldn't happen if the page didn't enter the BackForwardCache.
+crbug.com/991194 external/wpt/lifecycle/child-display-none.tentative.html [ Timeout ]
+crbug.com/991194 external/wpt/lifecycle/child-out-of-viewport.tentative.html [ Timeout ]
+crbug.com/991194 external/wpt/lifecycle/worker-dispay-none.tentative.html [ Failure ]