Duplicate AST node instead of popping it (#1143)
Duplicate AST node instead of popping it (#1143)

Popping an AST node modifies sibling links, which screws up parameter
counting for error checking in param_without_type.

Closes #1140.
kulibali/ponyc,boemmels/ponyc,ponylang/ponyc,Praetonus/ponyc,kulibali/ponyc,Perelandric/ponyc,Perelandric/ponyc,malthe/ponyc,mkfifo/ponyc,kulibali/ponyc,Theodus/ponyc,sgebbie/ponyc,malthe/ponyc,jupvfranco/ponyc,jupvfranco/ponyc,CausalityLtd/ponyc,CausalityLtd/ponyc,Perelandric/ponyc,cquinn/ponyc,jupvfranco/ponyc,ponylang/ponyc,boemmels/ponyc,dipinhora/ponyc,mkfifo/ponyc,boemmels/ponyc,jupvfranco/ponyc,jupvfranco/ponyc,dipinhora/ponyc,Perelandric/ponyc,jemc/ponyc,cquinn/ponyc,ponylang/ponyc,Theodus/ponyc,Theodus/ponyc,mkfifo/ponyc,jemc/ponyc,cquinn/ponyc,Perelandric/ponyc,malthe/ponyc,sgebbie/ponyc,Theodus/ponyc,mkfifo/ponyc,kulibali/ponyc,Praetonus/ponyc,cquinn/ponyc,malthe/ponyc,boemmels/ponyc,jemc/ponyc,dipinhora/ponyc,Theodus/ponyc,CausalityLtd/ponyc,mkfifo/ponyc,sgebbie/ponyc,Praetonus/ponyc,sgebbie/ponyc,Praetonus/ponyc,sgebbie/ponyc,boemmels/ponyc