VarHandle: add StaticFieldVarHandle class

Add StaticFieldVarHandle class to keep a live reference to the
declaring class for the target field of VarHandle's targeting static
fields.

Bug: 191980149
Test: art/test.py --host -r -g
Change-Id: I3a1cada6591d146b8f9fc9066105e3b617290185
9 files changed