please review fix for 4766230: invokevirtual override handling

[Florian Weimer]

* Karen Kinnear:

> • Problem 1: in debug: there are cases that assert "index out of
> bounds", and can crash in product mode.

> • This is because in hotspot, the calculation for vtable size is
> inconsistent with the calculation for adding vtable entries in the
> hotspot implementation.

Do you plan to backport this to (Open)JDK 6?  If yes, in what
timeframe?