use idweakmap for holding callbacks in browser

atom/common/api/lib/callbacks-registry.coffee

@@ -1,3 +1,5 @@
+v8Util = process.atomBinding 'v8_util'
+
 module.exports =
 class CallbacksRegistry
   constructor: ->
@@ -7,10 +9,6 @@ class CallbacksRegistry
   add: (callback) ->
     id = ++@nextId
 
-    for id,value of @callbacks
-      if value == callback
-        return id
-
     # Capture the location of the function and put it in the ID string,
     # so that release errors can be tracked down easily.
     regexp = /at (.*)/gi
@@ -21,10 +19,14 @@ class CallbacksRegistry
       continue if location.indexOf('(native)') isnt -1
       continue if location.indexOf('atom.asar') isnt -1
       [x, filenameAndLine] = /([^/^\)]*)\)?$/gi.exec(location)
-      id = "#{filenameAndLine} (#{id})"
       break
 
+    if v8Util.getHiddenValue(callback, 'metaId')?
+      return v8Util.getHiddenValue(callback, 'metaId')
+
     @callbacks[id] = callback
+    v8Util.setHiddenValue callback, 'metaId', id
+    v8Util.setHiddenValue callback, 'location', filenameAndLine
     id
 
   get: (id) ->