Remove SameSite features from driver.py

These SameSite features are enabled by default so we can clean them
up here.

Bug: 961439
Change-Id: I2a13a8abda97c3afcbb29f48e8d732e7a907f4d5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2493262
Commit-Queue: Steven Bingler <bingler@chromium.org>
Reviewed-by: Robert Ma <robertma@chromium.org>
Reviewed-by: Lily Chen <chlily@chromium.org>
Cr-Commit-Position: refs/heads/master@{#820235}

third_party/blink/tools/blinkpy/web_tests/port/driver.py

@@ -513,14 +513,6 @@ class Driver(object):
         if self._port.get_option('enable_leak_detection'):
             cmd.append('--enable-leak-detection')
 
-        # Run tests with the new SameSite cookie behavior by default.
-        # By appending the features to --enable-features, they will be enabled if
-        # they are not also explicitly disabled (as base::FeatureList disables a
-        # feature that appears in both --disable-features and --enable-features).
-        cmd.append(
-            '--enable-features=SameSiteByDefaultCookies,CookiesWithoutSameSiteMustBeSecure'
-        )
-
         cmd.extend(per_test_args)
         cmd = coalesce_repeated_switches(cmd)
         cmd.append('-')