hg: jdk/hs: 8190235: Clarify ClassLoaderData::is_*_class_loader_data() method implementations

[harold.seigel at oracle.com]

Changeset: 120d6893f32f
Author:    hseigel
Date:      2018-02-06 13:41 -0500
URL:       http://hg.openjdk.java.net/jdk/hs/rev/120d6893f32f

8190235: Clarify ClassLoaderData::is_*_class_loader_data() method implementations
Summary: Add comments, fix a small issue with the boot loader, and add an assert.
Reviewed-by: coleenp, lfoltan, gtriantafill

! src/hotspot/share/classfile/classLoaderData.cpp
! src/hotspot/share/classfile/classLoaderData.hpp
! src/hotspot/share/classfile/moduleEntry.hpp