Raise deprecation level for jsClass functions

Suppress error in tests

#KT-21703

js/js.translator/testData/box/reflection/jsClassName.kt

@@ -2,6 +2,7 @@
 // EXPECTED_REACHABLE_NODES: 1174
 package foo
 
+@Suppress("DEPRECATION_ERROR")
 fun testWithInstance() {
     assertEquals("A", A().jsClass.name)
     assertEquals("B", B().jsClass.name)
@@ -13,6 +14,7 @@ fun testWithInstance() {
     assertEquals("R", R().jsClass.name)
 }
 
+@Suppress("DEPRECATION_ERROR")
 fun testWithClassReference() {
     assertEquals("A", jsClass<A>().name)
     assertEquals("B", jsClass<B>().name)