Review request for JDK-8015668 : overload resolution: performance regression in JDK 7

[Vicente-Arturo Romero-Zaldivar]

Hello,

Please review this patch. It solves a performance regression in javac 
for 7u-dev repo.

The regression has been detected for a class that declares methods with 
a lot of parameters (1..254).

The proposed solution modifies a data structure used to store wrong 
method candidates for a given argument / type list. The mentioned data 
structure was a com.sun.tools.javac.util.List and now is a java.util.Set.

Also a new field has been added to MethodType in 
com.sun.tools.javac.code.Type this field stores the number of arguments 
so equal comparison between methods can now be done faster for evident 
cases.

The webrev is here:
http://cr.openjdk.java.net/~vromero/8015668_JDK7/webrev.00/

The bug report is here:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8015668

Thanks,
Vicente