importer: Split out the code that evaluates the script
importer: Split out the code that evaluates the script

from the one that defines it on the import object itself. We'll soon
use this to implement an alternate require(); syntax that aligns with
CommonJS.

mtwebster/cjs,mtwebster/cjs,pixunil/cjs,pixunil/cjs,mtwebster/cjs,endlessm/gjs,endlessm/gjs,pixunil/cjs,pixunil/cjs,endlessm/gjs,mtwebster/cjs,endlessm/gjs,pixunil/cjs,endlessm/gjs,mtwebster/cjs