(nobug) - Fixing mochitests logging fluent ReferenceErrors (#5147)

test/browser/browser.ini

@@ -7,7 +7,7 @@ prefs =
   browser.newtabpage.activity-stream.debug=false
   browser.newtabpage.activity-stream.discoverystream.endpoints=data:
   browser.newtabpage.activity-stream.feeds.section.topstories=true
-  browser.newtabpage.activity-stream.feeds.section.topstories.options={}
+  browser.newtabpage.activity-stream.feeds.section.topstories.options={"provider_name":""}
 
 [browser_aboutwelcome.js]
 [browser_activity_stream_strings.js]