Port OpenJDK8 java.util.*SummaryStatistics & add tests

Ported OpenJDK8 java.util.DoubleSummaryStatistics,
java.util.IntSummaryStatistics, java.util.LongSummaryStatistics.

Bug: 27426738

Change-Id: Ie8e3f7fc148615c38f2cf7bce971617599d00813
7 files changed