slashing: pay out gas cost of slashing from slashed amount

[ValarDragon]

The proposals in #1378 and #1440 could require a significant amount of gas on the person sending the transaction's end.

A method of making it so that these don't become a burden on the prover would be to provide a bounty that is clearly greater than the expected gas cost. So that this bounty doesn't come out of the validators money, it could instead come out of the slashed amount. (presuming the slashed amount is great enough)

[jackzampolin]

Going to close this issue as not applicable.

[ValarDragon]

Not sure why its not applicable? Its less significant sure, but it is still applicable. The person who reports a slash shouldn't have to pay for the slash's gas.

[jackzampolin]

Gas doesn't currently factor into slashing and the slashes happen automatically. Going to go ahead and close this issue.

[alexanderbez]

Within the evidence module we may have to be cognizant of the fact that a submitter of evidence shouldn't necessarily be charged for the tx. In fact, they may be rewarded.