(bug 43661) Added test for special link trail case

Parsoid is now constructing link trails based on a few rules, one of which
dealt with link prefixes. However, that caused some regressions that weren't
tested until now.

Change-Id: Id205589bb06bc5b290e67d4f4731f0e8e7215dee
Merge "(bug 43661) Added test for special link trail case"