Review: JDK 8 CR for Support Integer overflow updated

[Roger Riggs]

Updated the webrev for CR6708398:
          http://cr.openjdk.java.net/~rriggs/6708398.2
  - Added a paragraph to the class javadoc for Math and StrictMath to
    introduce the exact arithmetic methods and their uses.
  - Editorial correction to first sentence of each method to consistent 
use "Returns".
  - Added Tests for the StrictMath methods  (they are the same tests as 
for Math)

Thanks, Roger