Fix bug in net::RequestPriority -> HTTP/2 dependency conversion.

testing/variations/fieldtrial_testing_config_linux.json

 {
     "AsyncDNS": [
         {
             "group_name": "AsyncDNSA"
         }
     ],
     "AutofillClassifier": [
         {
             "group_name": "Enabled"
         }
@@ skipping 174 matching lines @@
     "SdchPersistence": [
         {
             "group_name": "Enabled"
         }
     ],
     "SimpleCacheTrial": [
         {
             "group_name": "ExperimentYes"
         }
     ],
-    "SpdyEnableDependencies": [
-        {
-            "group_name": "Enable"
-        }
-    ],
     "StrictSecureCookies": [
         {
             "group_name": "Enabled"
         }
     ],
     "SyncHttpContentCompression": [
         {
             "group_name": "Enabled"
         },
         {
@@ skipping 38 matching lines @@
     ],
     "use-new-media-cache": [
         {
             "enable_features": [
                 "use-new-media-cache"
             ],
             "group_name": "Enabled"
         }
     ]
 }