fixed bug with blockplacevent

Before this change line 105 and 106 stopped any changes made when changing the amount of items in a stack during the blockplaceevent.
Using this code http://pastebin.com/WcseU4Lh you can tell in previous versions that it gets overwritten by those lines.  Removing those two lines allows the code to function normally as it did before this change: https://github.com/Bukkit/CraftBukkit/commit/da3f36250c40a0a664cfc07d188d2b0c4985086f