RFR: JDK-8222151: refactoring: enhancements to java.lang.Class::methodToString and java.lang.Class::getTypeName

[Vicente Romero]

Please review the enhancements to java.lang.Class proposed by Sergei 
Tsypanov see discussion at [1]. The bug can be found at [2] and the fix 
at [3]. This enhancement is removing uses of StringBuilder in:
    ::toGenericString
    ::methodToString, and
    ::getTypeName
Thanks,
Vicente

[1] 
http://mail.openjdk.java.net/pipermail/core-libs-dev/2019-March/059110.html
[2] https://bugs.openjdk.java.net/browse/JDK-8222151
[3] http://cr.openjdk.java.net/~vromero/8222151/webrev.00/