md-highlight-flags: ^ and $ not working properly

[ivoviz]

Using md-autocomplete with custom template where we have multiple span tags with md-highlight-text and md-highlight-flags the ^ and $ flags don't work.

Pen here

Reproduce:

• Type 'd'

Only the first D should be red, but in fact, two more gets highlighted as well.
I can try and put together a PR if needed.

[devversion]

@ivoviz A PR is as always welcome.

Just let me know if you start working on that, otherwise someone of us would waste his time :)

[ivoviz]

@devversion I've just created a PR.