Add tests for generator intrinsic default proto (#636)

test/language/expressions/generators/default-proto.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-generator-function-definitions-runtime-semantics-evaluatebody
+es6id: 14.4.11
+description: Intrinsic default prototype of GeneratorFunctions
+info: |
+    1. Let G be ? OrdinaryCreateFromConstructor(functionObject,
+       "%GeneratorPrototype%", « [[GeneratorState]], [[GeneratorContext]] »).
+    [...]
+
+    9.1.13 OrdinaryCreateFromConstructor
+
+    [...]
+    2. Let proto be ? GetPrototypeFromConstructor(constructor,
+       intrinsicDefaultProto).
+    3. Return ObjectCreate(proto, internalSlotsList).
+
+    9.1.14 GetPrototypeFromConstructor
+
+    [...]
+    3. Let proto be ? Get(constructor, "prototype").
+    4. If Type(proto) is not Object, then
+       a. Let realm be ? GetFunctionRealm(constructor).
+       b. Let proto be realm's intrinsic object named intrinsicDefaultProto.
+    [...]
+---*/
+
+var g = function*() {};
+var GeneratorPrototype = Object.getPrototypeOf(g).prototype;
+g.prototype = null;
+
+assert.sameValue(Object.getPrototypeOf(g()), GeneratorPrototype);

test/language/statements/generators/default-proto.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-generator-function-definitions-runtime-semantics-evaluatebody
+es6id: 14.4.11
+description: Intrinsic default prototype of GeneratorFunctions
+info: |
+    1. Let G be ? OrdinaryCreateFromConstructor(functionObject,
+       "%GeneratorPrototype%", « [[GeneratorState]], [[GeneratorContext]] »).
+    [...]
+
+    9.1.13 OrdinaryCreateFromConstructor
+
+    [...]
+    2. Let proto be ? GetPrototypeFromConstructor(constructor,
+       intrinsicDefaultProto).
+    3. Return ObjectCreate(proto, internalSlotsList).
+
+    9.1.14 GetPrototypeFromConstructor
+
+    [...]
+    3. Let proto be ? Get(constructor, "prototype").
+    4. If Type(proto) is not Object, then
+       a. Let realm be ? GetFunctionRealm(constructor).
+       b. Let proto be realm's intrinsic object named intrinsicDefaultProto.
+    [...]
+---*/
+
+function* g() {}
+var GeneratorPrototype = Object.getPrototypeOf(g).prototype;
+g.prototype = null;
+
+assert.sameValue(Object.getPrototypeOf(g()), GeneratorPrototype);