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

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

@@ -0,0 +1,55 @@
+fun fn0() {}
+fun fn1(x: Any) {}
+
+val lambda0 = {} as () -> Unit
+val lambda1 = { x: Any -> } as (Any) -> Unit
+
+fun Any.extFun() {}
+
+var Any.extProp: String
+        get() = "extProp"
+        set(x: String) {}
+
+class A {
+    fun foo() {}
+}
+
+fun box(): String {
+    val f0 = ::fn0 as Any
+    val f1 = ::fn1 as Any
+
+    val ef = Any::extFun as Any
+    val epg = Any::extProp.getter
+    val eps = Any::extProp.setter
+
+    val afoo = A::foo
+
+    fun local0() {}
+    fun local1(x: Any) {}
+
+    val localFun0 = ::local0 as Any
+    val localFun1 = ::local1 as Any
+    
+    assert(f0 is Function0<*>) { "Failed: f0 is Function0<*>" }
+    assert(f1 is Function1<*, *>) { "Failed: f1 is Function1<*, *>" }
+    assert(f0 !is Function1<*, *>) { "Failed: f0 !is Function1<*, *>" }
+    assert(f1 !is Function0<*>) { "Failed: f1 !is Function0<*>" }
+
+    assert(lambda0 is Function0<*>) { "Failed: lambda0 is Function0<*>" }
+    assert(lambda1 is Function1<*, *>) { "Failed: lambda1 is Function1<*, *>" }
+    assert(lambda0 !is Function1<*, *>) { "Failed: lambda0 !is Function1<*, *>" }
+    assert(lambda1 !is Function0<*>) { "Failed: lambda1 !is Function0<*>" }
+
+    assert(localFun0 is Function0<*>) { "Failed: localFun0 is Function0<*>" }
+    assert(localFun1 is Function1<*, *>) { "Failed: localFun1 is Function1<*, *>" }
+    assert(localFun0 !is Function1<*, *>) { "Failed: localFun0 !is Function1<*, *>" }
+    assert(localFun1 !is Function0<*>) { "Failed: localFun1 !is Function0<*>" }
+
+    assert(ef is Function1<*, *>) { "Failed: ef is Function1<*, *>" }
+    assert(epg is Function1<*, *>) { "Failed: epg is Function1<*, *>"}
+    assert(eps is Function2<*, *, *>) { "Failed: eps is Function2<*, *, *>"}
+
+    assert(afoo is Function1<*, *>) { "afoo is Function1<*, *>" }
+
+    return "OK"
+}