Fix `test_should_sanitize_illegal_style_properties` failure

https://travis-ci.org/rails/rails/jobs/279300966#L2600

The result of `Loofah::HTML5::Scrub.scrub_css` was changed since
v2.1.0.rc1.

https://github.com/flavorjones/loofah/commit/ca56295ff9e802018ea18d23ed49be235a95ccad

actionview/test/template/sanitize_helper_test.rb

@@ -18,8 +18,8 @@ def test_sanitize_form
 
   def test_should_sanitize_illegal_style_properties
     raw      = %(display:block; position:absolute; left:0; top:0; width:100%; height:100%; z-index:1; background-color:black; background-image:url(http://www.ragingplatypus.com/i/cam-full.jpg); background-x:center; background-y:center; background-repeat:repeat;)
-    expected = %(display: block; width: 100%; height: 100%; background-color: black; background-x: center; background-y: center;)
-    assert_equal expected, sanitize_css(raw)
+    expected = %r(\Adisplay:\s?block;\s?width:\s?100%;\s?height:\s?100%;\s?background-color:\s?black;\s?background-x:\s?center;\s?background-y:\s?center;\z)
+    assert_match expected, sanitize_css(raw)
   end
 
   def test_strip_tags