Eliminate duplication between CODE_CALL and CODE_SUPER handling.
Eliminate duplication between CODE_CALL and CODE_SUPER handling.

Also improves perf:

binary_trees - wren            106.96% relative to baseline
delta_blue - wren               99.84% relative to baseline
fib - wren                     114.97% relative to baseline
for - wren                     123.32% relative to baseline
method_call - wren             112.80% relative to baseline
map_numeric - wren             111.36% relative to baseline
map_string - wren               93.73% relative to baseline
string_equals - wren           106.15% relative to baseline

foresterre/wren,foresterre/wren,Nave-Neel/wren,Nelarius/wren,munificent/wren,foresterre/wren,munificent/wren,minirop/wren,munificent/wren,Nelarius/wren,Rohansi/wren,minirop/wren,minirop/wren,munificent/wren,Nelarius/wren,Rohansi/wren,Nave-Neel/wren,Nelarius/wren,Nave-Neel/wren,bigdimboom/wren,bigdimboom/wren,Nelarius/wren,munificent/wren,Nave-Neel/wren,bigdimboom/wren,bigdimboom/wren,minirop/wren,foresterre/wren,minirop/wren,foresterre/wren,munificent/wren,Rohansi/wren,Rohansi/wren