Add self.reportError()

This allows libraries to emulate the behavior of an exception thrown in an event listener callback.

Additional context: whatwg/console#50.

Tests: web-platform-tests/wpt#29738.

Co-authored-by: Domenic Denicola <d@domenic.me>

source

@@ -91939,6 +91939,12 @@ document.querySelector("button").addEventListener("click", bound);
 
   <h5 id="runtime-script-errors">Runtime script errors</h5>
 
+  <dl class="domintro">
+   <dt>self . <code subdfn data-x="dom-reportError">reportError</code>( <var>e</var> )</dt>
+   <dd><p>Dispatches an <code data-x="event-error">error</code> event at the global object for the
+   given value <var>e</var>, in the same fashion as an unhandled exception.</p></dd>
+  </dl>
+
   <p w-dev>In various scenarios, the user agent can report an exception by firing an <code
   data-x="event-error">error</code> event at the <code>Window</code>. If this event is not canceled,
   then the error is considered not handled, and can be reported to the developer console.</p>
@@ -92034,6 +92040,10 @@ document.querySelector("button").addEventListener("click", bound);
   have known problems. You can track future cleanup in this area in <a
   href="https://github.com/whatwg/html/issues/958">issue #958</a>.</p>
 
+  <p>The <dfn method for="WindowOrWorkerGlobalScope"
+  data-x="dom-reportError"><code>reportError(<var>e</var>)</code></dfn> method steps are to
+  <span>report the exception</span> <var>e</var>.</p>
+
   <p id="the-errorevent-interface">The <code>ErrorEvent</code> interface is defined as follows:</p>
 
   <pre><code class="idl">[Exposed=(Window,Worker)]
@@ -95039,6 +95049,8 @@ interface mixin <dfn interface>WindowOrWorkerGlobalScope</dfn> {
   readonly attribute boolean <span data-x="dom-isSecureContext">isSecureContext</span>;
   readonly attribute boolean <span data-x="dom-crossOriginIsolated">crossOriginIsolated</span>;
 
+  undefined <span data-x="dom-reportError">reportError</span>(any e);
+
   // base64 utility methods
   DOMString <span data-x="dom-btoa">btoa</span>(DOMString data);
   ByteString <span data-x="dom-atob">atob</span>(DOMString data);