Remove test that CSSStyleSheet.media is read-only

style-sheet-interfaces-001.html tested that styleSheet.media was
read-only, but the spec changed to add a [PutForwards] attribute to
|media|, meanining that the attribute is no longer truly read-only.
assert_readonly can have side-effects if the property has a
[PutForwards] attribute, so remove this check, as it was causing the
next test to fail.

Bug: 821780
Change-Id: I77bee2f11484f6e679e4aee6b0641179c686d1d3
Reviewed-on: https://chromium-review.googlesource.com/989407Reviewed-by: Emil A Eklund <eae@chromium.org>
Commit-Queue: Chris Nardi <cnardi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547451}

third_party/WebKit/LayoutTests/external/wpt/css/cssom/style-sheet-interfaces-001-expected.txt

-This is a testharness.js-based test.
-PASS sheet_property
-PASS sheet_property_updates
-PASS CSSStyleSheet_properties
-PASS CSSStyleSheet_property_values
-PASS StyleSheet_properties
-FAIL StyleSheet_property_values assert_equals: expected "all" but got "alla"
-Harness: the test ran to completion.
-

third_party/WebKit/LayoutTests/external/wpt/css/cssom/style-sheet-interfaces-001.html

@@ -84,10 +84,9 @@
         assert_readonly(styleSheet, "parentStyleSheet");
         assert_readonly(styleSheet, "href");
         assert_readonly(styleSheet, "title");
-        assert_readonly(styleSheet, "media");
     }, "StyleSheet_properties",
     { assert: [ "type, disabled, ownerNode, parentStyleSheet, href, title, and media properties exist on StyleSheet",
-                "type, ownerNode, parentStyleSheet, href, title, media properties are read only" ] });
+                "type, ownerNode, parentStyleSheet, href, and title properties are read only" ] });
 
     test(function() {
         assert_equals(styleSheet.type, "text/css");