Reland of Use ES2015-style TypedArray prototype chain

test/mjsunit/es6/typedarray-proto.js

Index: test/mjsunit/es6/typedarray-proto.js
diff --git a/test/mjsunit/es6/typedarray-proto.js b/test/mjsunit/es6/typedarray-proto.js
index 558cb0ad7a25304b19c8d9fb41e893eba2c6195f..0bd90d13b404ca7befbac7817c8e688addf51f39 100644
--- a/test/mjsunit/es6/typedarray-proto.js
+++ b/test/mjsunit/es6/typedarray-proto.js
@@ -4,12 +4,10 @@
 
 // Test that the methods for different TypedArray types have the same
 // identity.
-// TODO(dehrenberg): Test that the TypedArray proto hierarchy is set
-// up properly.
-// TODO(dehrenberg): subarray is currently left out because that still
-// uses per-type methods. When that's fixed, stop leaving it out.
 
-var typedArrayConstructors = [
+'use strict';
+
+let typedArrayConstructors = [
   Uint8Array,
   Int8Array,
   Uint16Array,
@@ -20,6 +18,18 @@
   Float32Array,
   Float64Array];
 
+let TypedArray = Uint8Array.__proto__;
+let TypedArrayPrototype = TypedArray.prototype;
+
+assertEquals(TypedArray.__proto__, Function.prototype);
+assertEquals(TypedArrayPrototype.__proto__, Object.prototype);
+
+// There are extra own class properties due to it simply being a function
+let classProperties = new Set([
+  "length", "name", "arguments", "caller", "prototype", "BYTES_PER_ELEMENT"
+]);
+let instanceProperties = new Set(["BYTES_PER_ELEMENT", "constructor", "prototype"]);
+
 function functionProperties(object) {
   return Object.getOwnPropertyNames(object).filter(function(name) {
     return typeof Object.getOwnPropertyDescriptor(object, name).value
@@ -28,15 +38,33 @@
   });
 }
 
-var typedArrayMethods = functionProperties(Uint8Array.prototype);
-var typedArrayClassMethods = functionProperties(Uint8Array);
+let typedArrayMethods = functionProperties(Uint8Array.prototype);
+let typedArrayClassMethods = functionProperties(Uint8Array);
 
-for (var constructor of typedArrayConstructors) {
-  for (var method of typedArrayMethods) {
-    assertEquals(constructor.prototype[method],
-                 Uint8Array.prototype[method], method);
+for (let constructor of typedArrayConstructors) {
+  for (let property of Object.getOwnPropertyNames(constructor.prototype)) {
+    assertTrue(instanceProperties.has(property), property);
   }
-  for (var classMethod of typedArrayClassMethods) {
-    assertEquals(constructor[method], Uint8Array[method], classMethod);
+  for (let property of Object.getOwnPropertyNames(constructor)) {
+    assertTrue(classProperties.has(property), property);
   }
 }
+
+// Abstract %TypedArray% class can't be constructed directly
+
+assertThrows(() => new TypedArray(), TypeError);
+
+// The "prototype" property is nonconfigurable, nonenumerable, nonwritable,
+// both for %TypedArray% and for all subclasses
+
+let desc = Object.getOwnPropertyDescriptor(TypedArray, "prototype");
+assertFalse(desc.writable);
+assertFalse(desc.configurable);
+assertFalse(desc.enumerable);
+
+for (let constructor of typedArrayConstructors) {
+  let desc = Object.getOwnPropertyDescriptor(constructor, "prototype");
+  assertFalse(desc.writable);
+  assertFalse(desc.configurable);
+  assertFalse(desc.enumerable);
+}