Disable deprecations unless in dev/spec mode

These are currently adding ~200ms to startup so temporarily disable
until the grim performance is improved and/or core and bundled packages
are updated to not call deprecated APIs.

src/atom.coffee

@@ -158,6 +158,12 @@ class Atom extends Model
   #
   # Call after this instance has been assigned to the `atom` global.
   initialize: ->
+    # Disable deprecations unless in dev mode or spec mode so that regular
+    # editor performance isn't impacted by generating stack traces for
+    # deprecated calls.
+    unless @inDevMode() or @inSpecMode()
+      require('grim').deprecate = ->
+
     window.onerror = =>
       @openDevTools()
       @executeJavaScriptInDevTools('InspectorFrontendAPI.showConsole()')