hg: jdk/jdk: 8209087: Clean up runtime code that compares 'this' to NULL

[harold.seigel at oracle.com]

Changeset: 4e04b7ab20a3
Author:    hseigel
Date:      2018-10-18 10:35 -0400
URL:       http://hg.openjdk.java.net/jdk/jdk/rev/4e04b7ab20a3

8209087: Clean up runtime code that compares 'this' to NULL
Summary: Remove 'this' to NULL comparisons from methods and check if calling objects of these methods could be NULL.
Reviewed-by: lfoltan, gziemski

! src/hotspot/share/classfile/verificationType.cpp
! src/hotspot/share/oops/symbol.cpp
! src/hotspot/share/runtime/perfData.cpp
! src/hotspot/share/runtime/perfData.inline.hpp