Spellshock currently has the following wording in the Gatherer:
Whenever a player casts a spell, Spellshock deals 2 damage to that player.
However, the original wording shown in the card image is this:
Whenever any player successfully casts a spell, Spellshock deals 2 damage to him or her.
To me, the word "successfully" implies casting a spell which is not countered, though I'm not aware that the word "successfully" is ever defined in the rules. Otherwise, the word "successfully" means nothing at all, since it's pretty hard to fail at casting (as opposed to resolving) a spell. In more modern parlance, we might phrase the original ability this way:
Whenever a spell resolves and is not countered, Spellshock deals 2 damage to that spell's controller.
Is this the original intent of the card? If so, when and why was the wording changed?