Review for the new static ClassLoader.getPlatformClassLoader method

[Mandy Chung]

http://cr.openjdk.java.net/~mchung/jigsaw/webrevs/8146373/webrev.00/

This adds a new static ClassLoader.getPlatformClassLoader method to return a class loader via which all of the built-in Java SE and JDK types are visible.  This would be useful as several JDK modules are deprivileged.  To prepare for the future deprivileging work, this patch also relaxes the check such that java.* classes are defined by the platform class loader or its ancestor.

Mandy
[1] http://openjdk.java.net/projects/jigsaw/spec/issues/#PlatformClassLoader