Fix PortalRoot hiding the component's menus and tooltips

compound-web 10.4.0 treats a PortalRoot whose root is null as one whose root
is not available yet, so floating-ui never mounts the portal and every tooltip
label, and with it every icon button's accessible name, is missing. The
component defaulted portalRoot to null and wrapped the call unconditionally.

Wrap the call only when the host supplied a root, keeping null as the
not-yet-available case Compound defines, and say so on the prop. Cover it in
CallPortalRoot.test.tsx. Drop the git allowBuilds entry for compound-web now
that it is a release again.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

component/index.tsx

@@ -50,7 +50,7 @@ import {
 } from "react";
 import { logger } from "matrix-js-sdk/lib/logger";
 import { I18nextProvider } from "react-i18next";
-import { PortalRoot, TooltipProvider } from "@vector-im/compound-web";
+import { TooltipProvider } from "@vector-im/compound-web";
 import { ErrorBoundary } from "@sentry/react";
 import { shouldPolyfill as shouldPolyfillSegmenter } from "@formatjs/intl-segmenter/should-polyfill";
 import { shouldPolyfill as shouldPolyfillDurationFormat } from "@formatjs/intl-durationformat/should-polyfill.js";
@@ -82,6 +82,7 @@ import { useTheme } from "../src/useTheme";
 import { useStableValue } from "../src/useStableValue";
 import styles from "./ElementCall.module.css";
 import { useComponentHostBridge } from "./host";
+import { CallPortalRoot } from "./CallPortalRoot";
 import { type ElementCallProps } from "./api";
 import { supportedLanguages, translationsBackend } from "./localization";
 
@@ -154,7 +155,7 @@ export const ElementCall: FC<ElementCallProps> = ({
   ref,
   theme,
   language,
-  portalRoot = null,
+  portalRoot,
 }): ReactNode => {
   const hostBridge = useComponentHostBridge(suppliedHostBridge, ref, theme);
 
@@ -241,9 +242,7 @@ export const ElementCall: FC<ElementCallProps> = ({
               // Stands in for the standalone page's `#root`: see `.content`
               // in ElementCall.module.css
               <div className={styles.content}>
-                {/* Where Compound floats the call's menus and tooltips: the
-                host's body unless the host says otherwise (see `portalRoot`) */}
-                <PortalRoot root={portalRoot}>
+                <CallPortalRoot root={portalRoot}>
                   <RootElementProvider value={container}>
                     {/* Whatever goes wrong in here is shown in here. Left to
                     propagate, an error would unmount the host's own tree. */}
@@ -272,7 +271,7 @@ export const ElementCall: FC<ElementCallProps> = ({
                       </Decoration>
                     </ErrorBoundary>
                   </RootElementProvider>
-                </PortalRoot>
+                </CallPortalRoot>
               </div>
             )}
           </div>