Reviewed-by: Trust Me

The backwards scanner lazily tokenizes strings. This optimizes the
common case where scanning one or two lines is enough while at the same
time we extended the limit from 5 to 10 lines.

Reviewed-by: Roberto Raggi

Would show up when typing ")," where the closing brace doesn't have a
matching opening brace, for example.

Done with Roberto Raggi.

Done with Roberto Raggi.