Eliminate false 'inherits' warning on 'passthrough' type

[Chuck]

Get rid of this warning:

... a inherits B ...
warning: The expression (of type "passthrough") is never of type "Foo".

It comes up as part of error recovery, but you can simulate it:

class A

	def main is shared
		x as int = 1 to passthrough
		if x inherits A
			print 'A'

[hopscc]

Simulation doesnt gen same warning.
Did you mean

class A

	def main is shared
		x as passthrough = 1 
		if x inherits A
			print 'A'

[hopscc]

suppress warning if type is PassThrough?.

[Charles]

Patch applied in changeset:2952. Thanks.

Check-in comment:

Fixed: In compile-time error recovery situations, there are extraneous warnings regarding the inherits operator and the passthrough type.