Add tests for typedArrays extensibility

Ref: https://github.com/tc39/test262/pull/536#issuecomment-200455389

test/built-ins/TypedArrays/buffer-arg-new-instance-extensibility.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-typedarray-buffer-byteoffset-length
+description: >
+  The new typedArray instance from a buffer argument is extensible
+info: >
+  22.2.4.5 TypedArray ( buffer [ , byteOffset [ , length ] ] )
+
+  ...
+  4. Let O be ? AllocateTypedArray(constructorName, NewTarget,
+  "%TypedArrayPrototype%").
+  ...
+
+  22.2.4.2.1 Runtime Semantics: AllocateTypedArray (constructorName, newTarget,
+  defaultProto [ , length ])
+
+  ...
+  2. Let obj be IntegerIndexedObjectCreate(proto, « [[ViewedArrayBuffer]],
+  [[TypedArrayName]], [[ByteLength]], [[ByteOffset]], [[ArrayLength]] »).
+  ...
+
+  9.4.5.7 IntegerIndexedObjectCreate (prototype, internalSlotsList)
+
+  ...
+  11. Set the [[Extensible]] internal slot of A to true.
+  ...
+includes: [testTypedArray.js]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  var buffer = new ArrayBuffer(8);
+  var sample = new TA(buffer);
+
+  assert(Object.isExtensible(sample));
+});

test/built-ins/TypedArrays/length-arg-new-instance-extensibility.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-typedarray-length
+description: >
+  The new typedArray instance from a length argument is extensible
+info: >
+  22.2.4.2 TypedArray ( length )
+
+  This description applies only if the TypedArray function is called with at
+  least one argument and the Type of the first argument is not Object.
+
+  ...
+  8. Return ? AllocateTypedArray(constructorName, NewTarget,
+  %TypedArrayPrototype%, elementLength).
+
+  22.2.4.2.1 Runtime Semantics: AllocateTypedArray (constructorName, newTarget,
+  defaultProto [ , length ])
+
+  ...
+  2. Let obj be IntegerIndexedObjectCreate(proto, « [[ViewedArrayBuffer]],
+  [[TypedArrayName]], [[ByteLength]], [[ByteOffset]], [[ArrayLength]] »).
+  ...
+
+  9.4.5.7 IntegerIndexedObjectCreate (prototype, internalSlotsList)
+
+  ...
+  11. Set the [[Extensible]] internal slot of A to true.
+  ...
+includes: [testTypedArray.js]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  var sample = new TA(4);
+
+  assert(Object.isExtensible(sample));
+});

test/built-ins/TypedArrays/no-args-new-instance-extensibility.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-typedarray
+description: >
+  The new typedArray instance is extensible
+info: >
+  22.2.4.1 TypedArray( )
+
+  This description applies only if the TypedArray function is called with no
+  arguments.
+
+  ...
+  3. Return ? AllocateTypedArray(constructorName, NewTarget,
+  %TypedArrayPrototype%, 0).
+
+  22.2.4.2.1 Runtime Semantics: AllocateTypedArray (constructorName, newTarget,
+  defaultProto [ , length ])
+
+  ...
+  2. Let obj be IntegerIndexedObjectCreate(proto, « [[ViewedArrayBuffer]],
+  [[TypedArrayName]], [[ByteLength]], [[ByteOffset]], [[ArrayLength]] »).
+  ...
+
+  9.4.5.7 IntegerIndexedObjectCreate (prototype, internalSlotsList)
+
+  ...
+  11. Set the [[Extensible]] internal slot of A to true.
+  ...
+includes: [testTypedArray.js]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  var sample = new TA();
+
+  assert(Object.isExtensible(sample));
+});

test/built-ins/TypedArrays/object-arg-new-instance-extensibility.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-typedarray-object
+description: >
+  The new typedArray instance from an object argument is extensible
+info: >
+  22.2.4.4 TypedArray ( object )
+
+  ...
+  4. Let O be ? AllocateTypedArray(constructorName, NewTarget,
+  "%TypedArrayPrototype%").
+  ...
+
+  22.2.4.2.1 Runtime Semantics: AllocateTypedArray (constructorName, newTarget,
+  defaultProto [ , length ])
+
+  ...
+  2. Let obj be IntegerIndexedObjectCreate(proto, « [[ViewedArrayBuffer]],
+  [[TypedArrayName]], [[ByteLength]], [[ByteOffset]], [[ArrayLength]] »).
+  ...
+
+  9.4.5.7 IntegerIndexedObjectCreate (prototype, internalSlotsList)
+
+  ...
+  11. Set the [[Extensible]] internal slot of A to true.
+  ...
+includes: [testTypedArray.js]
+---*/
+
+var obj = {
+  "0": 0,
+  "1": 1,
+  "2": 2,
+  length: 3
+};
+
+testWithTypedArrayConstructors(function(TA) {
+  var sample = new TA(obj);
+
+  assert(Object.isExtensible(sample));
+});

test/built-ins/TypedArrays/typedarray-arg-new-instance-extensibility.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-typedarray-typedarray
+description: >
+  The new typedArray instance from a typedArray argument is extensible
+info: >
+  22.2.4.3 TypedArray ( typedArray )
+
+  ...
+  4. Let O be ? AllocateTypedArray(constructorName, NewTarget,
+  "%TypedArrayPrototype%").
+  ...
+
+  22.2.4.2.1 Runtime Semantics: AllocateTypedArray (constructorName, newTarget,
+  defaultProto [ , length ])
+
+  ...
+  2. Let obj be IntegerIndexedObjectCreate(proto, « [[ViewedArrayBuffer]],
+  [[TypedArrayName]], [[ByteLength]], [[ByteOffset]], [[ArrayLength]] »).
+  ...
+
+  9.4.5.7 IntegerIndexedObjectCreate (prototype, internalSlotsList)
+
+  ...
+  11. Set the [[Extensible]] internal slot of A to true.
+  ...
+includes: [testTypedArray.js]
+---*/
+
+var typedArraySample1 = new Int8Array();
+var typedArraySample2 = new Int8Array();
+Object.preventExtensions(typedArraySample2);
+
+testWithTypedArrayConstructors(function(TA) {
+  var sample1 = new TA(typedArraySample1);
+
+  assert(Object.isExtensible(sample1), "new instance is extensible");
+
+  var sample2 = new TA(typedArraySample2);
+  assert(
+    Object.isExtensible(sample2),
+    "new instance does not inherit extensibility from typedarray argument"
+  );
+});