Add APIs exposed in ShadowRealms

As discussed in today's meeting, this PR adds the `CustomEvent`,
`globalThis.reportError()` and `globalThis.self` APIs to the Minimum
Common API. This is done because they will be exposed in ShadowRealms
in browsers, and it is useful for code running in ShadowRealms to also
be able to run in server-side runtimes.

Author: andreubotella

index.bs

@@ -46,6 +46,7 @@ Interfaces:
 * {{CountQueuingStrategy}}
 * {{Crypto}}
 * {{CryptoKey}}
+* {{CustomEvent}}
 * <code class="idl"><a data-link-type="idl" href="https://wicg.github.io/compression/#decompression-stream">DecompressionStream</a></code>
 * {{DOMException}}
 * {{Event}}
@@ -98,6 +99,15 @@ Global methods / properties:
 * globalThis.{{performance}}.{{Performance/now()}}
 * globalThis.{{performance}}.{{timeOrigin}}
 * globalThis.{{queueMicrotask()}}
+* globalThis.{{reportError()}}
+* globalThis.self (on {{Window/self|Window}} and {{WorkerGlobalScope/self|WorkerGlobalScope}})
+
+    Note: This returns the value of `globalThis`.
+
+    Issue: When the <a href="https://github.com/whatwg/html/pull/9893">ShadowRealm integration PR</a>
+    is merged into the HTML spec,
+    `self` will also need to be exposed on `ShadowRealmGlobalScope`.
+
 * globalThis.{{setTimeout()}} / globalThis.{{clearTimeout()}}
 * globalThis.{{setInterval()}} / globalThis.{{clearInterval()}}
 * globalThis.{{structuredClone()}}