Add <usermedia> HTML element feature (#3983)

Issue: #3972

Author: ddbeck

features/usermedia.yml

@@ -0,0 +1,15 @@
+name: <usermedia>
+description: >
+  The `<usermedia>` HTML element represents a button that, upon activation, toggles camera or microphone streams.
+  If needed, it may prompt the user to choose whether to grant the page access to the camera and microphone.
+spec: https://github.com/WICG/PEPC/blob/main/usermedia_element.md
+# Expected:
+# compat_features:
+#   - api.HTMLUserMediaElement
+#   - api.HTMLUserMediaElement.HTMLUserMediaElement
+#   - api.HTMLUserMediaElement.stream
+#   - api.HTMLUserMediaElement.setConstraints
+#   - api.HTMLUserMediaElement.error
+#   - api.HTMLUserMediaElement.autostart
+#   - html.elements.usermedia
+#   - html.elements.usermedia.autostart

features/usermedia.yml.dist

@@ -0,0 +1,6 @@
+# Generated from: usermedia.yml
+# Do not edit this file by hand. Edit the source file instead!
+
+status:
+  baseline: false
+  support: {}

scripts/specs.ts

@@ -232,6 +232,10 @@ const defaultAllowlist: allowlistItem[] = [
         "https://wicg.github.io/shared-storage/",
         "Discontinued spec allowed for discouraged feature."
     ],
+    [
+        "https://github.com/WICG/PEPC/blob/main/usermedia_element.md",
+        "Replace with https://w3c.github.io/mediacapture-extensions/#the-usermedia-html-element when https://github.com/w3c/mediacapture-extensions/pull/168 merges."
+    ]
 ];
 
 function isOK(url: URL, allowlist: allowlistItem[] = defaultAllowlist) {