Request for reviews (S): 7045506: assert(!can_reshape || !new_phi) failed: for igvn new phi should be hooked

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/7045506/webrev

Fixed 7045506: assert(!can_reshape || !new_phi) failed: for igvn new phi should 
be hooked

After 7026700 fix LoadNode::split_through_phi() always creates a new split phi 
which causes this problem since the transformed load node could be a new node 
without users. In this bug case it is new LoadUB node created in AndINode::Ideal().

Replace the assert in PhiNode::Ideal with check to avoid transformation of new phi.