fix(material/dialog): dialog name not read on macOS chrome & firefox

Fixes Angular Components Dialog component where the dialog name is
not read by VoiceOver/screenreader on macOS chrome & firefox
browsers. Attempts to retrieve any id associated with aria-labelledby
or aria-describedby and taking the innerHTML or the aria-label of that
element and applying that value to the dialog's aria-label.

Fixes b/274674581

src/material/dialog/dialog-container.ts

@@ -26,9 +26,7 @@ import {
 import {MatDialogConfig} from './dialog-config';
 import {CdkDialogContainer} from '@angular/cdk/dialog';
 import {coerceNumberProperty} from '@angular/cdk/coercion';
-import {PlatformModule} from '@angular/cdk/platform';
 import {CdkPortalOutlet, ComponentPortal} from '@angular/cdk/portal';
-import {Observable, Subject, Subscription, defer, fromEvent, merge, of as observableOf} from 'rxjs';
 
 /** Event that captures the state of dialog container animations. */
 interface LegacyDialogAnimationEvent {
@@ -129,26 +127,27 @@ export class MatDialogContainer
   }
 
   /** Get Dialog name from aria attributes */
-  private _getDialogName = async (): Promise<void> => {
+  private _getDialogName = async (): Promise<string> => {
     const configData = this._config;
     /**_ariaLabelledByQueue and _ariaDescribedByQueue are created if ariaLabelledBy
-        or ariaDescribedBy values are applied to the dialog config
-    */
+        or ariaDescribedBy values are applied to the dialog config */
     const ariaLabelledByRefId = await this._ariaLabelledByQueue[0];
     const ariaDescribedByRefId = await this._ariaDescribedByQueue[0];
     /** Get Element to get name/title from if ariaLabelledBy or ariaDescribedBy */
     const dialogNameElement =
       document.getElementById(ariaLabelledByRefId) || document.getElementById(ariaDescribedByRefId);
     const dialogNameInnerText =
       /** If no ariaLabelledBy, ariaDescribedBy, or ariaLabel, create default aria label */
-      !dialogNameElement || !this._config.ariaLabel
+      !dialogNameElement && !this._config.ariaLabel
         ? 'Dialog Modal'
         : /** Otherwise prioritize use of ariaLabel */
           this._config.ariaLabel || dialogNameElement?.innerText || dialogNameElement?.ariaLabel;
-    return;
+    this._config.ariaLabel = dialogNameInnerText || 'Dialog Modal';
+    console.log(`getDialogName this.config.ariaLabel: `);
+    console.log(this._config.ariaLabel);
+    return this._config.ariaLabel;
   };
   ngAfterViewInit() {
-    const window = this._getWindow();
     this._getDialogName();
   }