Remove instance of 'blacklist' in W3CImportExpectations

Bug: None
Change-Id: Ie8254ad39fc5c97fb5d9cf3c009e175304c1d294

TBR=chrishtr@chromium.org

Change-Id: Ie8254ad39fc5c97fb5d9cf3c009e175304c1d294
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2159617Reviewed-by: Stephen McGruer <smcgruer@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: Stephen McGruer <smcgruer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#761144}

third_party/blink/web_tests/W3CImportExpectations

@@ -5,8 +5,8 @@
 
 # This file controls which subdirectories of the w3c test repos we import.
 #
-# This file acts as a blacklist; directories and files not listed here will
-# automatically be found and imported.
+# This file acts as a list of exclusions; directories and files not listed here
+# will automatically be found and imported.
 #
 # Tests that are imported but not run are listed in NeverFixTests. This can be
 # used to make it easier to work on getting them running and passing.