Revert "Issue #21 - Remove use counters telemetry"

This reverts commit 8ca9db6b65.

dom/base/UseCounters.conf

@@ -0,0 +1,63 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+// This file defines a list of use counters, which are things that can
+// record usage of Web platform features and then report this information
+// through Telemetry.
+//
+// The format of this file is very strict.  Each line can be:
+//
+//   (a) a blank line
+//
+//   (b) a comment, which is a line that begins with "//"
+//
+//   (c) one of three possible use counter declarations:
+//
+//         method <IDL interface name>.<IDL operation name>
+//         attribute <IDL interface name>.<IDL attribute name>
+//         property <CSS property method name>
+//
+// The |CSS property method name| should be identical to the |method|
+// argument to CSS_PROP and related macros.  The method name is
+// identical to the name of the property, except that all hyphens are
+// removed and CamelCase naming is used.  See nsCSSPropList.h for
+// further details.
+//
+// To actually cause use counters to be incremented, DOM methods
+// and attributes must have a [UseCounter] extended attribute in
+// the Web IDL file.  CSS properties require no special treatment
+// beyond being listed below.
+//
+// You might reasonably ask why we have this file and we require
+// annotating things with [UseCounter] in the relevant WebIDL file as
+// well.  Generating things from bindings codegen and ensuring all the
+// dependencies were correct would have been rather difficult, and
+// annotating the WebIDL files does nothing for identifying CSS
+// property usage, which we would also like to track.
+
+method SVGSVGElement.getElementById
+attribute SVGSVGElement.currentScale
+property Fill
+property FillOpacity
+
+// Push API
+method PushManager.subscribe
+method PushSubscription.unsubscribe
+
+// window.sidebar.addSearchEngine
+attribute Window.sidebar
+method External.addSearchEngine
+
+// AppCache API
+method OfflineResourceList.swapCache
+method OfflineResourceList.update
+attribute OfflineResourceList.status
+attribute OfflineResourceList.onchecking
+attribute OfflineResourceList.onerror
+attribute OfflineResourceList.onnoupdate
+attribute OfflineResourceList.ondownloading
+attribute OfflineResourceList.onprogress
+attribute OfflineResourceList.onupdateready
+attribute OfflineResourceList.oncached
+attribute OfflineResourceList.onobsolete