KT-4198 On covariant projection, do not throw whole var's away

#KT-4198 Fixed

compiler/testData/diagnostics/tests/generics/varProjection/setterNotProjectedOutAssign.kt

@@ -0,0 +1,11 @@
+trait Tr<T> {
+    var v: Tr<T>
+}
+
+fun test(t: Tr<*>) {
+    t.v = t
+    val v = TypeOf(t.v)
+    v: TypeOf<Tr<*>>
+}
+
+class TypeOf<T>(t: T)