Blacklist mail.google.com from top25_desk pageset

This will not lose coverage because we already have mail.google.com in Skia's
page sets.

NoTry: true
Bug: skia:7421
Change-Id: Ie3d335559e736e9177c9000f41dab25581230c8b
Reviewed-on: https://skia-review.googlesource.com/86500
Reviewed-by: Ravi Mistry <rmistry@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>

tools/skp/webpages_playback.py

@@ -107,6 +107,8 @@ CHROMIUM_PAGE_SETS_TO_PREFIX = {
 PAGE_SETS_TO_EXCLUSIONS = {
     # See skbug.com/7348
     'key_mobile_sites_smooth.py': '"(digg|worldjournal)"',
+    # See skbug.com/7421
+    'top_25_smooth.py': '"(mail\.google\.com)"',
 }