Add the first very basic bits of a geofencing API.

Source/modules/geolocation/CircularRegion.cpp

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "modules/geolocation/CircularRegion.h"
+
+#include "bindings/core/v8/Dictionary.h"
+
+namespace WebCore {
+
+CircularRegionInit::CircularRegionInit(const Dictionary& init)
+    : latitude(0)
+    , longitude(0)
+    , radius(0)
+{
+    init.get("id", id);

[Peter Beverloo, 2014/07/11 10:34:34]

You will likely have to rebase this on top of the following patch once it lands:
  https://codereview.chromium.org/373423002/

+    init.get("latitude", latitude);
+    init.get("longitude", longitude);
+    init.get("radius", radius);
+}
+
+CircularRegion* CircularRegion::create(const Dictionary& init)
+{
+    return new CircularRegion(CircularRegionInit(init));
+}
+
+CircularRegion::CircularRegion(const CircularRegionInit& init)
+    : GeofencingRegion(init.id)
+    , m_latitude(init.latitude)
+    , m_longitude(init.longitude)
+    , m_radius(init.radius)
+{
+    ScriptWrappable::init(this);

[Peter Beverloo, 2014/07/11 10:34:34]

We will end up calling ScriptWrappable::init() twice, since we also call it in
the GeofencingRegion constructor. Just remove it there?

+}
+
+} // namespace WebCore