Discriminate header classes in favor of non-header type aliases

In the test case, the problem was that Foo.a's type was resolved to the
_class A_, which was written to metadata on JVM instead of the class
AImpl with typealias A as an abbreviation. This metadata was incorrect
because there's no class A from the JVM compiler's point of view; that's
why the error "cannot access class A" was reported

 #KT-19151 Fixed

compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/AbstractLazyMemberScope.kt

@@ -69,13 +69,17 @@ protected constructor(
         // NB we should resolve type alias descriptors even if a class descriptor with corresponding name is present
         val classes = classDescriptors(name)
         val typeAliases = typeAliasDescriptors(name)
-        var resultingClass: ClassDescriptor? = null
+        // See getFirstClassifierDiscriminateHeaders()
+        var result: ClassifierDescriptor? = null
         for (klass in classes) {
-            // See getFirstClassifierDiscriminateHeaders()
             if (!klass.isHeader) return klass
-            if (resultingClass == null) resultingClass = klass
+            if (result == null) result = klass
         }
-        return resultingClass ?: typeAliases.firstOrNull()
+        for (typeAlias in typeAliases) {
+            if (!typeAlias.isHeader) return typeAlias
+            if (result == null) result = typeAlias
+        }
+        return result
     }
 
     override fun getContributedFunctions(name: Name, location: LookupLocation): Collection<SimpleFunctionDescriptor> {