Unable to bind e.g. A[0] if AA was also submitted

[dougbu]

Our value providers assume a candidate that's longer than a requested prefix is always greater than any potential match. This assumption is incorrect in some cases involving [ delimeters.

For example, with a <form></form> that submits data for A[0], AA[0], AA[1], and __RequestVerificationToken, A[0] will not be bound. This occurs because the submitted values are sorted AA[0], AA[1], A[0], then __RequestVerificationToken and AA[1] is the first candidate that's checked when looking for the A prefix.

The problem requires the binary search to land on just the right pivot e.g. A[0] is bound if a submission contains A[0], AA[0], and __RequestVerificationToken.

The problem should be specific to collections submitted with indexers.

[dougbu]

Self-assigning and placing in current milestone based on discussion w/ @rynowak

[dougbu]

f76a390