feat(extensions): BroadcastChannel WPT conformance

Replaces the file-backed provider by an in-memory one because proper
file locking is a hard problem that detracts from the proof of concept.

Teach the WPT runner how to extract tests from .html files because all
the relevant tests in test_util/wpt/webmessaging/broadcastchannel are
inside basics.html and interface.html.

1 files changed, 5 insertions, 0 deletions

diff --git a/extensions/web/02_event.js b/extensions/web/02_event.js
index b6b5609bc..8ee6acc61 100644
--- a/extensions/web/02_event.js
+++ b/extensions/web/02_event.js
@@ -1117,6 +1117,10 @@
   }
 
   class MessageEvent extends Event {
+    get source() {
+      return null;
+    }
+
     constructor(type, eventInitDict) {
       super(type, {
         bubbles: eventInitDict?.bubbles ?? false,
@@ -1208,5 +1212,6 @@
   };
   window.__bootstrap.event = {
     setIsTrusted,
+    setTarget,
   };
 })(this);