Add layout test to verify that global constructors in workers environment have right attributes

LayoutTests/webexposed/resources/global-constructors-attributes-worker.js

+if (this.importScripts)
+    importScripts('../../fast/js/resources/js-test-pre.js');
+
+description("Test to ensure that global constructors in workers environment have the right attributes");
+
+function descriptorShouldBe(object, property, expected) {
+    var test = "Object.getOwnPropertyDescriptor(" + object + ", " + property + ")";
+    if ("writable" in expected) {
+        shouldBe(test + ".value", "" + expected.value);
+        shouldBeFalse(test + ".hasOwnProperty('get')");
+        shouldBeFalse(test + ".hasOwnProperty('set')");
+    } else {
+        shouldBe(test + ".get", "" + expected.get);
+        shouldBe(test + ".set", "" + expected.set);
+        shouldBeFalse(test + ".hasOwnProperty('value')");
+        shouldBeFalse(test + ".hasOwnProperty('writable')");
+    }
+    shouldBe(test + ".enumerable", "" + expected.enumerable);
+    shouldBe(test + ".configurable", "" + expected.configurable);
+}
+
+var global = this;
+
+descriptorShouldBe("global", "'DataView'", {writable: true, enumerable: false, configurable: true, value:"DataView"});
+descriptorShouldBe("global", "'EventSource'", {writable: true, enumerable: false, configurable: true, value:"EventSource"});
+descriptorShouldBe("global", "'FileReaderSync'", {writable: true, enumerable: false, configurable: true, value:"FileReaderSync"});
+descriptorShouldBe("global", "'Float64Array'", {writable: true, enumerable: false, configurable: true, value:"Float64Array"});
+descriptorShouldBe("global", "'MessageChannel'", {writable: true, enumerable: false, configurable: true, value:"MessageChannel"});
+descriptorShouldBe("global", "'WorkerLocation'", {writable: true, enumerable: false, configurable: true, value:"WorkerLocation"});
+descriptorShouldBe("global", "'XMLHttpRequest'", {writable: true, enumerable: false, configurable: true, value:"XMLHttpRequest"});
+
+finishJSTest();