Whitespace
Fix source maps spec
Fix error message for missing dir/file in spec:* task
Regexp was missing `_isRegexp = true`
Fix String#index and add specs
Add #freeze #frozen? mocks, to make libs happy
fixup! Fix String#index and add specs
Add Enumerable#sort_by

Leaving one spec failing as a remainder to fix
multi values yields (e.g. yield(1,2,3)).
fixup! Add #freeze #frozen? mocks, to make libs happy
Fix source_map using mutable strings
0 or 1, as usual