Add tests for Subclassing the built-in TypedArray Objects

test/language/subclassing/TypedArray/regular-subclassing.js

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+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 22.2.4
+description: Subclassing TypedArrays
+info: >
+  22.2.4 The TypedArray Constructors
+
+  ...
+
+  The TypedArray constructors are designed to be subclassable. They may be used
+  as the value of an extends clause of a class definition. Subclass constructors
+  that intend to inherit the specified TypedArray behaviour must include a super
+  call to the TypedArray constructor to create and initialize the subclass
+  instance with the internal state necessary to support the
+  %TypedArray%.prototype built-in methods.
+---*/
+
+[
+  Int8Array,
+  Uint8Array,
+  Uint8ClampedArray,
+  Int16Array,
+  Uint16Array,
+  Int32Array,
+  Uint32Array,
+  Float32Array,
+  Float64Array
+].forEach(function(Constructor) {
+  class Typed extends Constructor {}
+
+  var arr = new Typed(2);
+
+  assert.sameValue(arr.length, 2);
+});

test/language/subclassing/TypedArray/super-must-be-called.js

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+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 22.2.4
+description: Super need to be called to initialize internals
+info: >
+  22.2.4 The TypedArray Constructors
+
+  ...
+
+  The TypedArray constructors are designed to be subclassable. They may be used
+  as the value of an extends clause of a class definition. Subclass constructors
+  that intend to inherit the specified TypedArray behaviour must include a super
+  call to the TypedArray constructor to create and initialize the subclass
+  instance with the internal state necessary to support the
+  %TypedArray%.prototype built-in methods.
+---*/
+
+[
+  Int8Array,
+  Uint8Array,
+  Uint8ClampedArray,
+  Int16Array,
+  Uint16Array,
+  Int32Array,
+  Uint32Array,
+  Float32Array,
+  Float64Array
+].forEach(function(Constructor) {
+  class Typed extends Constructor {
+    constructor() {}
+  }
+
+  assert.throws(ReferenceError, function() {
+    new Typed();
+  });
+
+  class TypedWithSuper extends Constructor {
+    constructor() {
+      super();
+    }
+  }
+
+  new TypedWithSuper();
+});