Added destroy to WebSocketProvider.

packages/providers/src.ts/websocket-provider.ts

@@ -274,4 +274,22 @@ export class WebSocketProvider extends JsonRpcProvider {
             this.send("eth_unsubscribe", [ subId ]);
         });
     }
+
+    async destroy(): Promise<void> {
+        // Wait until we have connected before trying to disconnect
+        if (this._websocket.readyState === WebSocket.CONNECTING) {
+            await new Promise((resolve) => {
+                this._websocket.on("open", () => {
+                    resolve(true);
+                });
+
+                this._websocket.on("error", () => {
+                    resolve(false);
+                });
+            });
+        }
+
+        // Hangup (navigating away from the page that opened the connection)
+        this._websocket.close(1001);
+    }
 }