Exclusions for PlzNavigate issues found on the Site Isolation Win bot.

NOTRY=true

Bug: 769502
Bug: 769508
Change-Id: Ib894feba443f5bbfbcd133f0ad73b9dd12e962ab
Tbr: alexmos@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/688223Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Cr-Commit-Position: refs/heads/master@{#504875}

third_party/WebKit/LayoutTests/FlagExpectations/site-per-process

 # These tests currently fail when they run with --site-per-process.
 # See https://crbug.com/477150.
 
+# https://crbug.com/769502: PlzNavigate-related, not-yet-investigated timeout.
+crbug.com/769502 fast/loader/recursive-before-unload-crash.html [ Timeout ]
+
+# https://crbug.com/769508: PlzNavigate-related, not-yet-investigated failures.
+crbug.com/769508 fast/css/acid2.html [ Failure ]
+crbug.com/769508 fast/css/acid2-pixel.html [ Failure ]
+
 # https://crbug.com/765779: unique name trouble with PlzNavigate
 crbug.com/765779 http/tests/loading/bad-server-subframe.html [ Failure ]
 crbug.com/765779 virtual/mojo-loading/http/tests/loading/bad-server-subframe.html [ Failure ]