Reduce length() calls on argument lists related to SubAssignArgs.


git-svn-id: https://svn.r-project.org/R/trunk@63658 00db46b3-68df-0310-9c12-caf00c1e9a41
Fixed NA handling in scalar relop code.


git-svn-id: https://svn.r-project.org/R/trunk@63659 00db46b3-68df-0310-9c12-caf00c1e9a41