getNodeKey with text nodes isn't supported?

[aleclarson]

This isn't a high priority bug, as I don't actually need getNodeKey to work with text nodes, but I noticed issues when trying it out, so it should probably be documented that getNodeKey should always return undefined for text nodes (or preferably, never call getNodeKey on text nodes in the first place). Or if the intention is to support this use case, a test should be added for it.

As I have a workaround, I don't have time to write a detailed report.