Support is/as/as? with Function[K]<...> types.

compiler/testData/codegen/boxWithStdlib/casts/reifiedSafeAsFunKSmall.kt

@@ -0,0 +1,41 @@
+fun fn0() {}
+fun fn1(x: Any) {}
+
+inline fun <reified T> reifiedSafeAsReturnsNonNull(x: Any?, operation: String) {
+    val y = try {
+        x as? T
+    }
+    catch (e: Throwable) {
+        throw AssertionError("$operation: should not throw exceptions, got $e")
+    }
+    if (y == null) {
+        throw AssertionError("$operation: should return non-null, got null")
+    }
+}
+
+inline fun <reified T> reifiedSafeAsReturnsNull(x: Any?, operation: String) {
+    val y = try {
+        x as? T
+    }
+    catch (e: Throwable) {
+        throw AssertionError("$operation: should not throw exceptions, got $e")
+    }
+    if (y != null) {
+        throw AssertionError("$operation: should return null, got $y")
+    }
+}
+
+fun box(): String {
+    val f0 = ::fn0 as Any
+    val f1 = ::fn1 as Any
+
+    reifiedSafeAsReturnsNonNull<Function0<*>>(f0, "f0 as Function0<*>")
+    reifiedSafeAsReturnsNull<Function1<*, *>>(f0, "f0 as Function1<*, *>")
+    reifiedSafeAsReturnsNull<Function0<*>>(f1, "f1 as Function0<*>")
+    reifiedSafeAsReturnsNonNull<Function1<*, *>>(f1, "f1 as Function1<*, *>")
+
+    reifiedSafeAsReturnsNull<Function0<*>>(null, "null as Function0<*>")
+    reifiedSafeAsReturnsNull<Function1<*, *>>(null, "null as Function1<*, *>")
+
+    return "OK"
+}