The convertNSStringToJString function convert NSString to Java String using NewStringUTF，NewStringUTF accept modified-UTF8 encoded str。This fix using UTF-16 encoding for converting.
------------- Commit messages: - fix input UTF-16 surrogate-pairs in macOS Changes: https://git.openjdk.java.net/jfx/pull/436/files Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=436&range=00 Issue: https://bugs.openjdk.java.net/browse/JDK-8258381 Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod Patch: https://git.openjdk.java.net/jfx/pull/436.diff Fetch: git fetch https://git.openjdk.java.net/jfx pull/436/head:pull/436 PR: https://git.openjdk.java.net/jfx/pull/436
