Before counting whitepsace-only `GlyphStore`s where counted as a single
justification opportunity when trimming whitespace from the front and
back of lines. This isn't correct, instead count the actual number of
word seperators of the trimmed `GlyphStore`s.
These two counts can be different in the case where whitespace collapse
isn't happening yet (flexbox). In addition, using word seperators means
the code is making less assumptions about the contents of the line and
is more robust.
This fixes some crashes in flexbox tests on debug builds.
Co-authored-by: Rakhi Sharma <atbrakhi@igalia.com>
This is just a bit of code movement that trims down the size of the
`inline.rs` file in order to make it a bit more manageable. It leads the
way to more refactoring and cleanup in the future.
