Regularize extended attributes on partial interfaces

Source/modules/mediasource/WindowMediaSource.idl

Index: Source/modules/mediasource/WindowMediaSource.idl
diff --git a/Source/modules/mediasource/WindowMediaSource.idl b/Source/modules/mediasource/WindowMediaSource.idl
index 6221f9e53b1aa10b5f8f8e09b44d85871190c43e..7d5eec67589f7b0ebdc15e46846a3dbbde01c347 100644
--- a/Source/modules/mediasource/WindowMediaSource.idl
+++ b/Source/modules/mediasource/WindowMediaSource.idl
@@ -27,8 +27,11 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
-partial interface Window {
-    [RuntimeEnabled=WebKitMediaSource] attribute WebKitMediaSourceConstructor WebKitMediaSource;
-    [RuntimeEnabled=WebKitMediaSource] attribute WebKitSourceBufferConstructor WebKitSourceBuffer;
-    [RuntimeEnabled=WebKitMediaSource] attribute WebKitSourceBufferListConstructor WebKitSourceBufferList;
+
+[
+    RuntimeEnabled=WebKitMediaSource,
+] partial interface Window {
+    attribute WebKitMediaSourceConstructor WebKitMediaSource;
+    attribute WebKitSourceBufferConstructor WebKitSourceBuffer;
+    attribute WebKitSourceBufferListConstructor WebKitSourceBufferList;
 };