RFR: 8220496: Race in java_lang_String::length() when deduplicating

[Roman Kennke]

Looks good! Thanks!

Roman

> Hi,
> 
> a few asserts in java_lang_String can trigger when deduplicating
> Strings. The fix is to ensure we assert using a deeper equals on the
> contents of the value.  Moving the method already implemented to do this
> in StringDedupTable to java_lang_String seems to be in order, along with
> a few cleanups.
> 
> Webrev: http://cr.openjdk.java.net/~redestad/8220496/open.00/
> Bug:    https://bugs.openjdk.java.net/browse/JDK-8220496
> 
> Testing: tier1-3
> 
> Thanks!
> 
> /Claes