Remove commented typeMustMatch attribute from <object>

This just removes one commented out line. There are no functional
changes.

typeMustMatch was removed from the HTML spec here:
whatwg/html#4590

I don't believe any other browser implemented this.

Bug: 897442
Change-Id: I543a8c84273bfbfef6d9ff2225a49fa1d1105965
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3413353
Commit-Queue: Joey Arhar <jarhar@chromium.org>
Reviewed-by: Mason Freed <masonf@chromium.org>
Cr-Commit-Position: refs/heads/main@{#962645}

third_party/blink/renderer/core/html/html_object_element.idl

@@ -29,7 +29,6 @@
 ] interface HTMLObjectElement : HTMLElement {
     [CEReactions, Reflect, URL, RaisesException=Setter] attribute ScriptURLString data;
     [CEReactions, Reflect] attribute DOMString type;
-    // TODO(foolip): attribute boolean typeMustMatch;
     [CEReactions, Reflect] attribute DOMString name;
     [CEReactions, Reflect] attribute DOMString useMap;
     [ImplementedAs=formOwner] readonly attribute HTMLFormElement? form;