Request for reviews (S): 6851282: JIT miscompilation results in null entry in array when using CompressedOops

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/6851282/webrev.00

Fixed 6851282: JIT miscompilation results in null entry in array when using CompressedOops

Problem:
PhiNode::Ideal() has optimization which pushes DecodeN node
down through Phi. But it may set incorrect type (TOP) for
new Phi node when it use DecodeN's input on dead path.

Solution:
Get type for new Phi from non dead path.

Reviewed by:

Fix verified (y/n): y, bug's test

Other testing:
JPRT