Remove loadStylesheets from non-theme pckage activate()

src/atom-package.coffee

@@ -68,7 +68,6 @@ class AtomPackage extends Package
 
   activate: ({immediate}={}) ->
     @measure 'activateTime', =>
-      @loadStylesheets()
       @activateResources()
       if @metadata.activationEvents? and not immediate
         @subscribeToActivationEvents()

src/theme-package.coffee

@@ -23,3 +23,8 @@ class ThemePackage extends AtomPackage
       catch e
         console.warn "Failed to load theme named '#{@name}'", e.stack ? e
     this
+
+  activate: ->
+    @measure 'activateTime', =>
+      @loadStylesheets()
+      @activateNow()