Make item and namedItem args in MimeTypeArray/PluginArray/Plugin non-optional

third_party/WebKit/Source/modules/plugins/MimeTypeArray.idl

Index: third_party/WebKit/Source/modules/plugins/MimeTypeArray.idl
diff --git a/third_party/WebKit/Source/modules/plugins/MimeTypeArray.idl b/third_party/WebKit/Source/modules/plugins/MimeTypeArray.idl
index 9854da4f32dd14426342ce700d678642db08438c..5344fddc2b4e61b2e6f1042001e12782ccefdbc5 100644
--- a/third_party/WebKit/Source/modules/plugins/MimeTypeArray.idl
+++ b/third_party/WebKit/Source/modules/plugins/MimeTypeArray.idl
@@ -18,11 +18,13 @@
     Boston, MA 02110-1301, USA.
 */
 
+// https://html.spec.whatwg.org/multipage/webappapis.html#mimetypearray
+
 [
     ImplementedAs=DOMMimeTypeArray
 ] interface MimeTypeArray {
     readonly attribute unsigned long length;
-    getter MimeType item([Default=Undefined] optional unsigned long index);
-    MimeType namedItem([Default=Undefined] optional DOMString name);
-    [NotEnumerable, ImplementedAs=namedItem] getter MimeType ([Default=Undefined] optional DOMString name);
+    // TODO(lunalu): the return type should be nullable.

[foolip, 2017/03/21 08:57:52]

You can just make that change, it won't affect the generated code, or at least
it wouldn't have last time I tried a change like this.

+    getter MimeType item(unsigned long index);
+    [NotEnumerable] getter MimeType namedItem(DOMString name);
 };