Add finch configuration for the OfflinePagesSvelte finch test.

testing/variations/fieldtrial_testing_config.json

Index: testing/variations/fieldtrial_testing_config.json
diff --git a/testing/variations/fieldtrial_testing_config.json b/testing/variations/fieldtrial_testing_config.json
index 1ebd4ac609e2779b7420fd2d25956a701ea3a073..2e3bad0e608c063d6c2f1e3db08715d85318a0e5 100644
--- a/testing/variations/fieldtrial_testing_config.json
+++ b/testing/variations/fieldtrial_testing_config.json
@@ -1322,6 +1322,12 @@
                     "enable_features": [
                         "OfflinePagesAsyncDownload"
                     ]
+                },
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "OfflinePagesSvelte"

[jianli, 2017/01/26 01:32:34]

Should this be merged into above entries?

[Steven Holte, 2017/01/26 21:59:39]

Yes, assuming these will be controlled by the same finch config.  Just move
"OfflinePagesSvelte" into the enabled_features list.

[Pete Williamson, 2017/01/28 01:29:13]

Done.

+                    ]
                 }
             ]
         }