[11u] RFR: 8255544: Create a checked cast

[Doerr, Martin]

Hi,

JDK-8255544 is backported to 11.0.11-oracle. I'd like to backport it for parity. And it's required by other backports.
Change doesn't apply cleanly:
globalDefinitions.hpp: I had to apply the hunk manually because of unrelated context changes.
heap.cpp: Doesn't apply because JDK-8231460 is not in 11u. I suggest to skip it.

Bug:
https://bugs.openjdk.java.net/browse/JDK-8255544

Original change:
https://github.com/openjdk/jdk/commit/3302d3ad

11u backport:
http://cr.openjdk.java.net/~mdoerr/8255544_checked_cast_11u/webrev.00/

Please review.

Best regards,
Martin