Remove support for PushSubscription.subscriptionId.

Source/platform/exported/WebPushSubscription.cpp

+// Copyright 2015 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 "public/platform/modules/push_messaging/WebPushSubscription.h"
+
+#include "platform/weborigin/KURL.h"
+#include "wtf/text/WTFString.h"
+
+namespace blink {
+
+WebPushSubscription::WebPushSubscription(const WebString& endpointWithoutSubscriptionId, const WebString& subscriptionId)
+{
+    String concatenatedEndpoint = endpointWithoutSubscriptionId;
+    concatenatedEndpoint.append("/");
+    concatenatedEndpoint.append(subscriptionId);
+
+    endpoint = KURL(ParsedURLString, concatenatedEndpoint);
+}
+
+} // namespace blink