Add 'close' to EventClient and PollingClient

src/lib.rs

@@ -203,6 +203,10 @@ impl PollingClient {
     pub fn send_binary(&self, message: Vec<u8>) -> Result<(), JsValue> {
         self.event_client.send_binary(message)
     }
+
+    pub fn close(&self) -> Result<(), JsValue> {
+        self.event_client.close();
+    }
 }
 
 #[derive(Debug, Clone, Error)]
@@ -435,4 +439,8 @@ impl EventClient {
             .borrow()
             .send_with_u8_array(message.as_slice())
     }
+
+    pub fn close(&self) -> Result<(), JsValue> {
+        self.connection.borrow().close()
+    }
 }