cros: Disable more mash_browser_tests on mojo FYI bot

In preparation for moving the main waterfall mash_browser_tests from
its narrow whitelist to the larger FYI blacklist.

Bug: 678687
Test: browser_tests
Change-Id: I61d512ccb1ba4152cb2ae99a022b4e8cf92c67b6
Reviewed-on: https://chromium-review.googlesource.com/891997Reviewed-by: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532713}

testing/buildbot/filters/mojo.fyi.mash.browser_tests.filter

@@ -64,9 +64,12 @@
 -CaptivePortalWindowTest.*
 -SimpleWebViewDialogTest.*
 
-# Need pixel copy support. http://crbug.com/754864
+# Need pixel copy support. http://crbug.com/754864 http://crbug.com/754872
+-ArcAccessibilityHelperBridgeBrowserTest.*
+-CastStreamingApiTest.*
 -CastStreamingApiTestWithPixelOutput.*
 -TabCaptureApiPixelTest.*
+-TabCaptureApiTest.*
 
 # RefCounted check failed: CalledOnValidSequence() from SchedulerWorkerDelegate::OnMainExit
 -CheckSystemTokenAvailability/EnterprisePlatformKeysTest.*