RFR 8027640 : String.indexOf(String,int) for the empty string case not specified

[Brent Christian]

Please review my changes for:
https://bugs.openjdk.java.net/browse/JDK-8027640

The webrev is here:
http://cr.openjdk.java.net/~bchristi/8027640/webrev.00/


This is a small cleanup to reconcile the String[last]indexOf() spec with 
longstanding behavior.  There are no changes to executable code.

In String, the "Math.min(fromIndex, this.length())" clause is brought 
over from String[Buffer|Builder] for indexOf(String,int) and 
lastIndexOf(String,int).  This resolves the issue for which the bug was 
filed.

To further sync up the [last]indexOf() docs, I ported the 6940381 
wording improvements from String to String[Buffer|Builder].  I also made 
a few doclint updates to the code in question.

Thanks,
-Brent