[quickview] Document openQuickViewDocumentsProvider test issue

The test does not actually display the text file in test. Document the
bug and error symptom (site not reached error shown in the preview).

Make the test return IGNORE_APP_ERRORS: fixing issue 1064855 causes it
to fail because the reason for the error is detected earlier, and will
log a console.error and hence FAIL this test.

Bug: 1131298, 1064855
Change-Id: I5351cf572bcf2ec3399ed7ad7130029f99209dc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2423756
Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: Alex Danilo <adanilo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809696}

ui/file_manager/integration_tests/file_manager/quick_view.js

@@ -528,6 +528,10 @@
 
     // Open a DocumentsProvider file in Quick View.
     await openQuickView(appId, ENTRIES.hello.nameText);
+
+    // crbug.com/1131298 The text file content is not displayed. The <webview>
+    // instead shows a "site cannot be reached" error.
+    return IGNORE_APP_ERRORS;
   };
 
   /**