commit f3fa0d604ef6527a01dab96f4bfa3c5290127337
Author: Markus Scherer <markus.icu@gmail.com>
Date:   Fri Nov 9 12:54:22 2018 -0800

    ICU-20250 make UnicodeSet(intprop=value) faster
    - fastpath for UnicodeSet.add(new last range)
    - fewer UnicodeSet memory allocations:
      initial internal list array, exponential array growth,
      allocate strings list/set only when first one is added
    - faster CodePointTrie.getRange(): fewer calls to filter function
    - revert UnicodeSet(intprop=value) from trie ranges to range starts + lookup
    - cache per-int-prop range starts: fewer lookups
    
    (cherry picked from commit 98f9170004c29388d756a8a283573164a7a26bef)