Fix possible race by unlocking mutex earlier

This is unlikely but we should give up the mutex early just in case we
use it where ever EventFrameNavigation event is consumed.

Resolves: #630 (comment)

Author: ankur22

common/frame_manager.go

@@ -122,12 +122,13 @@ func (m *FrameManager) frameAbortedNavigation(frameID cdp.FrameID, errorText, do
 	}
 
 	frame.pendingDocumentMu.Lock()
-	defer frame.pendingDocumentMu.Unlock()
 
 	if frame.pendingDocument == nil {
+		frame.pendingDocumentMu.Unlock()
 		return
 	}
 	if documentID != "" && frame.pendingDocument.documentID != documentID {
+		frame.pendingDocumentMu.Unlock()
 		return
 	}
 
@@ -142,6 +143,9 @@ func (m *FrameManager) frameAbortedNavigation(frameID cdp.FrameID, errorText, do
 		err:         errors.New(errorText),
 	}
 	frame.pendingDocument = nil
+
+	frame.pendingDocumentMu.Unlock()
+
 	frame.emit(EventFrameNavigation, ne)
 }