Fix crash when using class property write helpers with FPC

This patch resolves two issues regarding FPC compatibility:
1) FPC expects a pointer to a TMethod object in the next-best register (EDX here). PascalScript used to push the whole TMethod onto the stack. EDX was always zero, resulting in an access violation.
2) Someone forgot commenting out a line in uPSRuntime.pas:10878, leading to inevitable doom after returning from the property write helper.