Enable pointer events on waterfall.

testing/variations/fieldtrial_testing_config_linux.json

 {
     "AsyncDNS": [
         {
             "group_name": "AsyncDNSA"
         }
     ],
     "AutofillClassifier": [
         {
             "group_name": "Enabled"
         }
@@ skipping 143 matching lines @@
         }
     ],
     "PasswordSeparatedSigninFlow": [
         {
             "enable_features": [
                 "UsePasswordSeparatedSigninFlow"
             ],
             "group_name": "Enabled"
         }
     ],
+    "PointerEvent": [
+        {
+            "enable_features": [
+                "PointerEvent"
+            ],
+            "group_name": "Enabled"
+        }
+    ],
     "PreconnectMore": [
         {
             "enable_features": [
                 "PreconnectMore"
             ],
             "group_name": "Enabled"
         }
     ],
     "QUIC": [
         {
@@ skipping 189 matching lines @@
     ],
     "use-new-media-cache": [
         {
             "enable_features": [
                 "use-new-media-cache"
             ],
             "group_name": "Enabled"
         }
     ]
 }