JS stdlib api test: various changes

- Setting -Doverwrite.output=true updates gold data
- Big packages don't get split into chunks
- Unique lines in the API are marked with /*∆*/ and diff test is removed
- Annotations on separate lines and other dump format tweaks
- Test data moved to libraries/stdlib/api/
- Minor visibility fix to Enum members

libraries/stdlib/api/js/kotlin.properties.kt

@@ -0,0 +1,34 @@
+public object Delegates {
+    public final fun <T : kotlin.Any> notNull(): kotlin.properties.ReadWriteProperty<kotlin.Any?, T>
+
+    public final inline fun <T> observable(initialValue: T, crossinline onChange: (property: kotlin.reflect.KProperty<*>, oldValue: T, newValue: T) -> kotlin.Unit): kotlin.properties.ReadWriteProperty<kotlin.Any?, T>
+
+    public final inline fun <T> vetoable(initialValue: T, crossinline onChange: (property: kotlin.reflect.KProperty<*>, oldValue: T, newValue: T) -> kotlin.Boolean): kotlin.properties.ReadWriteProperty<kotlin.Any?, T>
+}
+
+public abstract class ObservableProperty<V> : kotlin.properties.ReadWriteProperty<kotlin.Any?, V> {
+    public constructor ObservableProperty<V>(initialValue: V)
+
+    protected open fun afterChange(property: kotlin.reflect.KProperty<*>, oldValue: V, newValue: V): kotlin.Unit
+
+    protected open fun beforeChange(property: kotlin.reflect.KProperty<*>, oldValue: V, newValue: V): kotlin.Boolean
+
+    public open override operator fun getValue(thisRef: kotlin.Any?, property: kotlin.reflect.KProperty<*>): V
+
+    public open override operator fun setValue(thisRef: kotlin.Any?, property: kotlin.reflect.KProperty<*>, value: V): kotlin.Unit
+}
+
+@kotlin.SinceKotlin(version = "1.4")
+public interface PropertyDelegateProvider<in T, out D> {
+    public abstract operator fun provideDelegate(thisRef: T, property: kotlin.reflect.KProperty<*>): D
+}
+
+public interface ReadOnlyProperty<in T, out V> {
+    public abstract operator fun getValue(thisRef: T, property: kotlin.reflect.KProperty<*>): V
+}
+
+public interface ReadWriteProperty<in T, V> : kotlin.properties.ReadOnlyProperty<T, V> {
+    public abstract override operator fun getValue(thisRef: T, property: kotlin.reflect.KProperty<*>): V
+
+    public abstract operator fun setValue(thisRef: T, property: kotlin.reflect.KProperty<*>, value: V): kotlin.Unit
+}