Implement DeviceLight

LayoutTests/fast/dom/DeviceLight/script-tests/add-during-dispatch.js

+description('Test no fire listeners added during event dispatch.');
+
+var mockEvent;
+function setMockLight(value) {
+
+    mockEvent = {value: value};
+
+    if (window.testRunner)
+        testRunner.setMockDeviceLight(null != mockEvent.value, null == mockEvent.value ? 0 : mockEvent.value);
+    else
+        debug('This test can not be run without the TestRunner');
+}
+
+var deviceLightEvent;
+function checkLight(event) {
+    deviceLightEvent = event;
+    shouldBe('deviceLightEvent.value', 'mockEvent.value');
+}
+
+function firstListener(event) {
+    checkLight(event);
+    window.removeEventListener('devicelight', firstListener);
+    window.addEventListener('devicelight', secondListener);
+    setTimeout(function(){finish();}, 100);
+}
+
+var numSecondListenerCalls = 0;
+function secondListener(event) {
+    ++numSecondListenerCalls;
+}
+
+function finish() {
+    shouldBe('numSecondListenerCalls', '1');
+    finishJSTest();
+}
+
+setMockLight(10);
+window.addEventListener('devicelight', firstListener);
+
+window.jsTestIsAsync = true;