`imported_source_files` adjusts lots of file positions, and then calls `new_imported_source_file`, which then adjust them all again. This commit combines the two adjustments into one, for a small perf win.
`imported_source_files` adjusts lots of file positions, and then calls `new_imported_source_file`, which then adjust them all again. This commit combines the two adjustments into one, for a small perf win.