This change adds D8 in addition to Dx which is being deprecated.
At some point after the official Dx deprecation, we should remove
the Dx checker.
Moving to D8 has the additional benefit that D8 can dex code
using java 8 features without using a separate desugaring tool.
Currently FirThisReceiverExpression of instance methods are translated
to references of the class' thisReceiver,
not the method's dispatch receiver,
which causes problems with IrFrameMap::typeOf,
as the class' thisReceiver is not in the typeMap.
This commit translates non-qualified "this" references of
instance methods to references of the methods' dispatch receiver.
Artem Kobzar