Link uri encoding, URL-escaping should be left alone inside the destination

[mym0404]

Fix #597

By the Commonmark Spec URL-escaping should be left alone inside the destination, reimplement normalizeLinkDestination util function with splitting by URL Escapings and concatenating them again.

We shouldn't use decodeXXX at initial string in any ways.

This doesn't make problem with fixed issue #589. All tests previous exist also are passed.

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[mym0404]

I renewed Google CLA. It should work now

[coveralls]

Pull Request Test Coverage Report for Build 8335977223

Details

• 6 of 6 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.01%) to 96.147%

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Totals
Change from base Build 8223548919:	0.01%
Covered Lines:	1547
Relevant Lines:	1609

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💛 - Coveralls

[srawlins]

Thanks so much for the fix! One suggestion

[srawlins]

I think this work of tracking the matches and the splitIterator can be simplified with splitMapJoin. Something like:

return destination.splitMapJoin(regex,
    onMatch: (m) => m.input,
    onNonMatch: (e) {
      try {
        e = Uri.decodeFull(e);
      } catch (_) {}
      return Uri.encodeFull(decodeHtmlCharacters(e));
    },
);

WDYT?

[mym0404]

I haven't heard splitMapJoin. Thank you for your suggestion. I refactored.

[srawlins]

Slick!