RFR 8203381 Replace InstanceKlass::allocate_instance_handle with JavaCalls::construct_new_instance

[Ioi Lam]

https://bugs.openjdk.java.net/browse/JDK-8203381
http://cr.openjdk.java.net/~iklam/jdk11/8203381-construct-new-instance.v01/

This patch removes a lot of the boilerplate code for allocating a
Java object and calling its constructor. Hopefully the code is cleaner
and easier to read.

Also:

Added assert(InstanceKlass::is_initialized(), ...) in case where
we cannot call JavaCalls::construct_new_instance for thread objects.

Replaced unnecessary SystemDictionary::resolve_or_null() calls with
SystemDictionary::XXX_klass().

Tested with hs-tier[1,2,3,4,5]

Thanks
- Ioi