Highlight element that failed checksum

[davidgilbertson]

At the moment, when the server-rendered markup doesn't match the client-rendered markup, a big red error is shown, but it can be difficult/impossible to locate the element where this occurred.

Would something that logged the offending element to the console be considered as a pull request?

master...davidgilbertson:log-checksum-failed-element

[gaearon]

This sounds interesting. We don't do checksum validation anymore in 16 but still need to report differences. I mentioned this approach in #10085 so let's keep the discussion there.