RFR: 8214784: Adjust Dictionary and JNIHandle verification

[coleen.phillimore at oracle.com]

Also looks good.
Coleen

On 12/4/18 7:53 AM, Per Liden wrote:
> Dictionary::verify() and JNIHandles::verify() currently do 
> verification that is unnecessary and incorrect. It currently calls 
> oopDesc::verify(), which not only checks the oop, but also steps out 
> into the heap to verify the actual object and its fields. This is 
> unnecessary because this is already taken care of by 
> CollectedHeap::verify(). It's also incorrect, because when stepping 
> out into the heap you need to ahead to various Barrier/GC 
> restrictions, which the code currently doesn't do. To fix this, the 
> verification done in Dictionary::verify() and JNIHandles::verify() 
> should only check the oop, not the object and its fields.
>
> In this patch, I'm also cleaning out a ZGC specific check in the JNI 
> verification, which skipped verification of JNI weaks. This check is 
> no longer needed after JDK-8212921.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8214784
> Webrev: http://cr.openjdk.java.net/~pliden/8214784/webrev.0
>
> /Per