Revert "Fix cannot find context with specified id"

Although this commit fixes most of the problems,
we don't know the implications of this change. So
it's better to revert it.

This reverts commit 4f95b1b.

Author: inancgumus

common/frame_session.go

@@ -785,7 +785,7 @@ func (fs *FrameSession) onAttachedToTarget(event *target.EventAttachedToTarget)
 	session := fs.page.browserCtx.conn.getSession(event.SessionID)
 	targetID := event.TargetInfo.TargetID
 
-	if eti := event.TargetInfo; eti.Type == "iframe" && eti.URL != "" {
+	if event.TargetInfo.Type == "iframe" {
 		frame := fs.manager.getFrameByID(cdp.FrameID(targetID))
 		if frame == nil {
 			return