LoadL->ConvL2I ==> LoadI optimization causes the problem for an object
initialization after InitializeNode was added in C2 since LoadI will not
match raw StoreL captured by InitializeNode. As result LoadI node could
be scheduled above the initialize StoreL node.
The problem was found during EA testing.
1. Remove LoadL->ConvL2I ==> LoadI optimization.
2. Remove code in MemNode::Ideal_common() which allows a Load node
bypass initialize Store node after macro expansion of Initialize node.