The source code position cache was moved from a line based approach
to a "chunk"-based approach to improve performance on large, minified
JavaScript files with few lines, but this has had an adverse effect
on _multi-line_ source files.
Reintroduce some of the old behaviour by caching lines again, with
some added sanity limits to avoid caching empty/overly small lines.
Source code positions in files with few lines will still be cached
less often, since minified JavaScript files can be assumed to be
unusually large, and since stack traces for minified JavaScript
are less useful as well.
On WPT tests with large JavaScript dependencies like
`css/css-masking/animations/clip-interpolation.html` this reduces the
amount of time spent in `SourceCode::range_from_offsets` by as much as
99.98%, for the small small price of 80KB extra memory usage.
