Revert "Be more efficient with String.fromCharCodes (dart-lang/source_span#44)" (dart-lang/source_span#46)

This reverts commit ff838908bd75a6b3c1d8cebdb42b7b96f06e9c42.

This caused an unknown issue in rare cases with the test package.
1 file changed
tree: b1124f7fed20654f79c7ef38bff07ff452b48b5c
  1. pkgs/