Add window.requireStylesheet

This allows you to synchronously load a stylesheet into the document's
head whenever it is needed.

spec/atom/window-spec.coffee

@@ -1,5 +1,5 @@
-require 'window'
 $ = require 'jquery'
+fs = require 'fs'
 
 describe "Window", ->
   describe "keybindings", ->
@@ -15,6 +15,23 @@ describe "Window", ->
         $(window).trigger 'close'
         expect(window.close).toHaveBeenCalled()
 
+    describe "requireStylesheet(path)", ->
+      it "synchronously loads the stylesheet at the given path and installs a style tag for it in the head", ->
+        $('head style').remove()
+        expect($('head style').length).toBe 0
+        requireStylesheet('atom.css')
+        expect($('head style').length).toBe 1
+
+        styleElt = $('head style')
+
+        fullPath = require.resolve('atom.css')
+        expect(styleElt.attr('path')).toBe fullPath
+        expect(styleElt.text()).toBe fs.read(fullPath)
+
+        requireStylesheet('atom.css')
+        expect($('head style').length).toBe 1
+
+
     describe "bindMenuItem(path, keyPattern, action)", ->
       it "causes the given menu item to be added to the menu when the window is focused and removed when it is blurred", ->
         addedPaths = []

spec/spec-helper.coffee

@@ -3,11 +3,13 @@ $ = require 'jquery'
 _ = require 'underscore'
 Native = require 'native'
 BindingSet = require 'binding-set'
+require 'window'
 
 afterEach ->
   (new Native).resetMainMenu()
   atom.globalKeymap.reset()
   $('#jasmine-content').empty()
+  $('head style[path]').remove()
 
 window.atom = new (require 'app')
 

src/atom/window.coffee

@@ -1,6 +1,7 @@
 fs = require 'fs'
 _ = require 'underscore'
 $ = require 'jquery'
+fs = require 'fs'
 
 RootView = require 'root-view'
 
@@ -25,6 +26,12 @@ windowAdditions =
     $(window).unbind('focus')
     $(window).unbind('blur')
 
+  requireStylesheet: (path) ->
+    fullPath = require.resolve(path)
+    content = fs.read(fullPath)
+    return if $("head style[path='#{fullPath}']").length
+    $('head').append "<style path='#{fullPath}'>#{content}</style>"
+
   bindMenuItems: ->
     # we want to integrate this better with keybindings
     # @bindMenuItem "File > Save", "meta+s", => @rootView.editor.save()