Implementing test cases for object rest deconstruction

Closes #867
Ref #865

src/dstr-binding/obj-ptrn-rest-obj-nested-rest.case

+// Copyright (C) 2017 Caio Lima. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+desc: >
+    When DestructuringAssignmentTarget is an object literal, it should be parsed
+    parsed as a DestructuringAssignmentPattern and evaluated as a destructuring
+    assignment and object rest desconstruction is allowed in that case.
+template: default
+esid: pending
+includes: [propertyHelper.js]
+---*/
+
+//- elems
+{a, b, ...{c, ...rest}}
+//- vals
+{a: 1, b: 2, c: 3, d: 4, e: 5}
+//- body
+assert.sameValue(a, 1);
+assert.sameValue(b, 2);
+assert.sameValue(c, 3);
+
+assert.sameValue(rest.d, 4);
+assert.sameValue(rest.e, 5);
+
+verifyEnumerable(rest, "d");
+verifyWritable(rest, "d");
+verifyConfigurable(rest, "d");
+
+verifyEnumerable(rest, "e");
+verifyWritable(rest, "e");
+verifyConfigurable(rest, "e");
+

src/dstr-binding/obj-ptrn-rest-obj-own-property.case

+// Copyright (C) 2017 Caio Lima. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+desc: >
+    Rest object contains just soruce object's own properties
+template: default
+esid: pending
+includes: [propertyHelper.js]
+---*/
+
+//- setup
+var o = Object.create({ x: 1, y: 2 });
+o.z = 3;
+//- elems
+{ x, ...{y , z} }
+//- vals
+o
+//- body
+assert.sameValue(x, 1);
+assert.sameValue(y, undefined);
+assert.sameValue(z, 3);
+

src/dstr-binding/obj-ptrn-rest-skip-non-enumerable.case

+// Copyright (C) 2017 Caio Lima. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+desc: >
+    Rest object doesn't contain non-enumerable properties
+template: default
+esid: pending
+includes: [propertyHelper.js]
+---*/
+
+//- setup
+var o = {a: 3, b: 4};
+Object.defineProperty(o, "x", { value: 4, enumerable: false });
+//- elems
+{...rest}
+//- vals
+o
+//- body
+assert.sameValue(rest.a, 3);
+assert.sameValue(rest.b, 4);
+assert.sameValue(rest.x, undefined);
+
+verifyEnumerable(rest, "a");
+verifyWritable(rest, "a");
+verifyConfigurable(rest, "a");
+
+verifyEnumerable(rest, "b");
+verifyWritable(rest, "b");
+verifyConfigurable(rest, "b");
+

src/dstr-binding/obj-ptrn-rest-val-obj.case

+// Copyright (C) 2017 Caio Lima. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+desc: >
+    Rest object contains just unextracted data
+template: default
+esid: pending
+includes: [propertyHelper.js]
+---*/
+
+//- elems
+{a, b, ...rest}
+//- vals
+{x: 1, y: 2, a: 5, b: 3}
+//- body
+assert.sameValue(rest.x, 1);
+assert.sameValue(rest.y, 2);
+assert.sameValue(rest.a, undefined);
+assert.sameValue(rest.b, undefined);
+
+verifyEnumerable(rest, "x");
+verifyWritable(rest, "x");
+verifyConfigurable(rest, "x");
+
+verifyEnumerable(rest, "y");
+verifyWritable(rest, "y");
+verifyConfigurable(rest, "y");
+