Skip redundant resize in init_shape_functions
Skip redundant resize in init_shape_functions

This shaves 2-5% off benchmark runtimes for me.

BalticPinguin/libmesh,capitalaslash/libmesh,jwpeterson/libmesh,roystgnr/libmesh,capitalaslash/libmesh,capitalaslash/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,roystgnr/libmesh,roystgnr/libmesh,libMesh/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,roystgnr/libmesh,capitalaslash/libmesh,libMesh/libmesh,BalticPinguin/libmesh,dschwen/libmesh,dschwen/libmesh,roystgnr/libmesh,capitalaslash/libmesh,capitalaslash/libmesh,capitalaslash/libmesh,roystgnr/libmesh,libMesh/libmesh,capitalaslash/libmesh,dschwen/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,dschwen/libmesh,jwpeterson/libmesh,BalticPinguin/libmesh,libMesh/libmesh,dschwen/libmesh,libMesh/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,dschwen/libmesh,BalticPinguin/libmesh,dschwen/libmesh,libMesh/libmesh,roystgnr/libmesh,jwpeterson/libmesh,libMesh/libmesh,roystgnr/libmesh,dschwen/libmesh,jwpeterson/libmesh,libMesh/libmesh