don't delete session

lib/frame-tree/content/content-frame-tree.js

@@ -147,7 +147,7 @@ this.frameTree = this.frameTree || (() => {
 					}
 					windowData.resolve(windowData.frames);
 				}
-				sessions.delete(message.sessionId);
+				//sessions.delete(message.sessionId);
 			}
 		}
 	}