RFR 8164632: Node indices should be treated as unsigned integers

[Eric, Chan]

Hi,

Requesting review for

Webrev : http://cr.openjdk.java.net/~xliu/eric/8164632/00/webrev/
JBS : https://bugs.openjdk.java.net/browse/JDK-8164632

The change cast uint ni to integer so that the parameter that pass to method TypeOopPtr::cast_to_instance_id is a integer.

I have tested this builds successfully .

Ensured that there are no regressions in hotspot : tier1 tests.

Regards,
Eric Chen