JS: support reified usage in extension functions

js/js.translator/testData/reified/cases/extensionFun.kt

@@ -0,0 +1,17 @@
+package foo
+
+// CHECK_NOT_CALLED: canBeCastedTo
+
+open class A
+class B
+class C : A()
+
+inline fun Any.canBeCastedTo<reified T>(): Boolean = this is T
+
+fun box(): String {
+    assertEquals(true, A().canBeCastedTo<A>(), "A().canBeCastedTo<A>()")
+    assertEquals(false, A().canBeCastedTo<B>(), "A().canBeCastedTo<B>()")
+    assertEquals(true, C().canBeCastedTo<A>(), "C().canBeCastedTo<A>()")
+
+    return "OK"
+}