Add initial Blink-side support for the Screen Orientation API

Source/core/frame/Screen.cpp

Index: Source/core/frame/Screen.cpp
diff --git a/Source/core/frame/Screen.cpp b/Source/core/frame/Screen.cpp
index bc9184948bc1c3b855ce513e74aa6c43951dbfec..67283acac6e3be568a25bbdd4a14b3cf687d2ee9 100644
--- a/Source/core/frame/Screen.cpp
+++ b/Source/core/frame/Screen.cpp
@@ -120,4 +120,16 @@ unsigned Screen::availWidth() const
     return static_cast<unsigned>(screenAvailableRect(m_frame->view()).width());
 }
 
+const AtomicString& Screen::interfaceName() const
+{
+    return EventTargetNames::Screen;
+}
+
+ExecutionContext* Screen::executionContext() const
+{
+    if (!m_frame)
+        return 0;
+    return m_frame->document();
+}
+
 } // namespace WebCore