annouce first drop target after drag start (#3191)

Co-authored-by: Robert Snow <rsnow@adobe.com>

Author: reidbarber

packages/@react-aria/dnd/src/DragManager.ts

@@ -157,6 +157,7 @@ class DragSession {
   private restoreAriaHidden: () => void;
   private formatMessage: (key: string) => string;
   private isVirtualClick: boolean;
+  private initialFocused: boolean;
 
   constructor(target: DragTarget, formatMessage: (key: string) => string) {
     this.dragTarget = target;
@@ -168,6 +169,7 @@ class DragSession {
     this.onClick = this.onClick.bind(this);
     this.onPointerDown = this.onPointerDown.bind(this);
     this.cancelEvent = this.cancelEvent.bind(this);
+    this.initialFocused = false;
   }
 
   setup() {
@@ -446,6 +448,13 @@ class DragSession {
 
       item?.element.focus();
       this.currentDropItem = item;
+
+      // Annouce first drop target after drag start announcement finishes.
+      // Otherwise, it will never get announced because drag start announcement is assertive.
+      if (!this.initialFocused) {
+        announce(item?.element.getAttribute('aria-label'), 'polite');
+        this.initialFocused = true;
+      }
     }
   }