[GAMEPLAY] Champions can cast spells after teleporting inside Soraka's E

If a champion teleports inside an active silence zone from Soraka's E, he is still able to cast abilities for a fraction of a second. This is enough for some to escape the zone using dashes or blinks, completely nullifying the effects of the silence. Happens every game, and is consistent. Works with all teleport effects. Steps for reproduction:

1. Play Soraka
2. Enemy starts teleporting on a target (e.g. a ward)
3. Place silence on top of the target as teleport is about to finish (3 seconds after the channel starts is enough for an SS Teleport)
4. Enemy arrives and can use abilities for about 0.1-0.2 seconds

This is obviously unintended behavior and should be fixed.