Stop using DOMError

[foolip]

DOMError is gone from https://dom.spec.whatwg.org/ and we're looking to get rid of it in Blink:
https://code.google.com/p/chromium/issues/detail?id=460725

CC @annevk (DOM) and @inexorabletash (IndexedDB has a similar situation)

[inexorabletash]

In https://w3c.github.io/IndexedDB/ I just s/DOMError/DOMException/g but we haven't landed that yet. I think we're waiting on seeing usage numbers around DOMError that @foolip added, but maybe our "intent" thread just got forgotten.

[foolip]

Not forgotten, but waiting for this counter to reach stable in M45:
https://www.chromestatus.com/metrics/feature/timeline/popularity/816

These are also interesting, but not worrying compat-wise:
https://www.chromestatus.com/metrics/feature/timeline/popularity/817
https://www.chromestatus.com/metrics/feature/timeline/popularity/818

[inexorabletash]

We just landed the s/DOMError/DOMException/g change Indexed DB in Chrome. Hopefully it sticks.

[Ms2ger]

@mkruisselbrink could you fix?

[inexorabletash]

In Blink we converted FileReader over to use DOMException for the error attribute back in July 2016 and the change stuck, so I think we can go ahead and update the spec.