Remove allowConnectingInsecureWebSocket Settings item

Source/core/frame/Settings.in

 # Defines properties which are available on the Settings object.
 #
 # Please think carefully before adding a new Setting.  Some questions to
 # consider are:
 # - Should this be a RuntimeEnabledFeature instead? Settings are for things
 #   which we support either values of at runtime.  Features are set at renderer
 #   process startup and are never changed. Features also tend to be set to a
 #   value based on the platform or the stability of the code in question, where
 #   as settings both codepaths need to be stable.
 # - How will you ensure test coverage of all relevant values of your setting?
@@ skipping 87 matching lines @@
 
 # WebAudio support.
 webAudioEnabled initial=false
 
 asynchronousSpellCheckingEnabled initial=false
 
 hyperlinkAuditingEnabled initial=false
 allowDisplayOfInsecureContent initial=true
 allowRunningOfInsecureContent initial=true
 
-# FIXME: Remove this temporary flag. See crbug.com/366483 for the target
-# milestone.
-allowConnectingInsecureWebSocket initial=false
 mediaControlsOverlayPlayButtonEnabled initial=false
 mediaPlaybackRequiresUserGesture initial=false
 
 scrollAnimatorEnabled initial=true
 
 # Used to disable threaded, compositor scrolling for testing purposes.
 # crbug.com/410974 tracks removal once alternative solutions for selective
 # main thread scrolling are supported.
 threadedScrollingEnabled initial=true, invalidate=Style
 
@@ skipping 203 matching lines @@
 useMobileViewportStyle initial=false, invalidate=ViewportRule
 
 # User style overrides for captions and subtitles
 textTrackBackgroundColor type=String
 textTrackFontFamily type=String
 textTrackFontStyle type=String
 textTrackFontVariant type=String
 textTrackTextColor type=String
 textTrackTextShadow type=String
 textTrackTextSize type=String