Erroneous fix reverted. Test added

compiler/testData/checkerWithErrorTypes/quick/regressions/UnavaliableQualifiedThis.jet

@@ -0,0 +1,13 @@
+trait Iterator<out T> {
+ fun next() : T
+ val hasNext : Boolean
+
+ fun <R> map(transform: fun(element: T) : R) : Iterator<R> =
+    object : Iterator<R> {
+      override fun next() : R = transform(<!NO_THIS!>this@map<!>.next())
+
+      override val hasNext : Boolean
+        // There's no 'this' associated with the map() function, only this of the Iterator class
+        get() = <!NO_THIS!>this@map<!>.hasNext
+    }
+}