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

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

 /*
     Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
     Copyright (C) 2008 Apple Inc. All rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.
 
     This library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Library General Public License for more details.
 
     You should have received a copy of the GNU Library General Public License
     along with this library; see the file COPYING.LIB.  If not, write to
     the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     Boston, MA 02110-1301, USA.
 */
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#plugins-2
 
 [
     ImplementedAs=DOMPlugin
 ] interface Plugin {
     readonly attribute DOMString name;
     readonly attribute DOMString filename;
     readonly attribute DOMString description;
     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);
+    getter MimeType? item(unsigned long index);
+    [NotEnumerable] getter MimeType? namedItem(DOMString name);

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

Adding [NotEnumerable] here should change the enumerability of the namedItem
method, which we don't want. I don't know why [NotEnumerable] was used
originally below, but just omitting should be fine, because by definition an
anonymous getter doesn't have a name to enumerate.

[lunalu1, 2017/03/21 17:56:50]

I tried to do it without NotEnumerable, but the generated code was changed and
also
required additional implementation of namedPRopertyQuery and
namedPropertyEnumerator.
LegacyUnenumerableNamedProperties suggests that named properties shouldn't be
enumerable:
https://heycam.github.io/webidl/#LegacyUnenumerableNamedProperties

[foolip, 2017/03/22 05:04:52]

Ah, I missed the [LegacyUnenumerableNamedProperties] on the interface level.
https://software.hixie.ch/utilities/js/live-dom-viewer/?saved=4962 shows that
the namedItem name is enumerable, so adding [NotEnumerable] here would change
that.

I guess the only choice is to remove [NotEnumerable] here and to keep the second
line for now, exception the argument doesn't need to be optional.

I filed https://bugs.chromium.org/p/chromium/issues/detail?id=703990, can you
add a TODO to use it here?

[lunalu1, 2017/03/24 15:42:17]

"If the [LegacyUnenumerableNamedProperties] extended attribute appears on a
interface that supports named properties, it indicates that all the interface’s
named properties are unenumerable"?

Our WebIDL compiler indicates that by an attribute on the named property getter
rather than one on the interface. But isn't it functionally equivalent?

[foolip, 2017/03/30 04:52:21]

Not entirely, it seems like [NotEnumerable] also suppresses the generation of a
namedPropertyQuery call, which I think should still work even if things aren't
enumerable.

[lunalu1, 2017/03/30 18:32:03]

I see. I guess for now we will just keep both the getter and the the method.

+    // [NotEnumerable, ImplementedAs=namedItem] getter MimeType ([Default=Undefined] optional DOMString name);

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

Remove this line rather than commenting it out.

 };