Errors when submitting addblock form by keypress (Bug 1336529)

Pushing enter when not on the submit or cancel buttons causes an error

Change-Id: I10a861ed5825c877a13a73a54fd4244d7bfd6cab
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>
Merge "Errors when submitting addblock form by keypress (Bug 1336529)"