Can't find keyframes anywhere, but I can see their effect I have set two keyframes for the image texture node's offset property, which are driving the animation of that image texture.

After trying to use the NLA, I seem to have completely lost these two keyframes. I have two strips in the NLA but hitting tab to edit them doesn't reveal the keyframes for the offset property. Their effect is still seen, as witnessed by the changing offsrt value.

What's going in this blender file? How did I manage to make two keyframes completely disappear from any editor?

Here's the file:

https://drive.google.com/file/d/0Bz8CfnsnifVvNUhnM0MybnRkQ0E/view?usp=sharing
This seems to be a problem just with you. I downloaded the file and the keyframes were still visible. Don't know what it could be; maybe close the .blend file and reopen it.

Hope this helps!