Fix lack of screen reader indication when triggering auto complete (#10664)

Author: t3chguy

Diff for: src/components/views/rooms/BasicMessageComposer.tsx

@@ -798,7 +798,7 @@ export default class BasicMessageEditor extends React.Component<IProps, IState>
         };
 
         const { completionIndex } = this.state;
-        const hasAutocomplete = Boolean(this.state.autoComplete);
+        const hasAutocomplete = !!this.state.autoComplete;
         let activeDescendant: string | undefined;
         if (hasAutocomplete && completionIndex! >= 0) {
             activeDescendant = generateCompletionDomId(completionIndex!);
@@ -828,7 +828,7 @@ export default class BasicMessageEditor extends React.Component<IProps, IState>
                     aria-multiline="true"
                     aria-autocomplete="list"
                     aria-haspopup="listbox"
-                    aria-expanded={hasAutocomplete ? true : undefined}
+                    aria-expanded={hasAutocomplete ? !this.autocompleteRef.current?.state.hide : undefined}
                     aria-owns={hasAutocomplete ? "mx_Autocomplete" : undefined}
                     aria-activedescendant={activeDescendant}
                     dir="auto"