Fix stringContainsInOrder to account for repetitions and empty strings

[aliak00]

No description provided.

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[aliak00]

@googlebot I signed it!

[jakemac53]

This should actually be this probably right?

Suggested change

	fromIndex = item.indexOf(s, fromIndex) + 1;
	fromIndex = item.indexOf(s, fromIndex) + s.length;

[jakemac53]

Oh except that wouldn't work when you get -1. But the current implementation also isn't correct, for instance I think we should have this test:

shouldFail('foo', stringContainsInOrder(['fo', 'oo']));

Which I think would (unexpectedly) pass in the current implementation?

[aliak00]

Ah true. Good catch! Will fix and push update soon!

[jakemac53]

How about this?

Suggested change

	if (s.isEmpty) continue;
	fromIndex = item.indexOf(s, fromIndex) + 1;
	if (fromIndex <= 0) return false;
	var index = item.indexOf(s, fromIndex);
	if (index < 0) return false;
	fromIndex = index + s.length;

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[jakemac53]

Note that we may have to revert this, at least temporarily, if it causes too much breakage in existing tests in the Dart/Flutter sdks or internal tests.

[jakemac53]

@googlebot I consent