Use instanceof trick for consistent construction style

Fixes #67.

docs/coding_standards.txt

@@ -8,6 +8,13 @@ Most of iD is written with [a js module pattern](http://macwright.org/2012/06/04
 that is, they do not use the `new` operator, and they use scope instead of
 `this` to reference variables and functions.
 
+The exceptions are classes that are very heavily instantiated: Graphs and entities. These are written in a
+classical manner for [performance reasons](https://gist.github.com/3961693).
+
+In order to unify the construction interface for these two styles, classical classes use the
+[instanceof trick](http://ejohn.org/blog/simple-class-instantiation/). This allows instantiation
+of both module pattern classes and classical classes to be done without using `new`.
+
 Function names
 --------------
 Anything that creates and calls an Action should be prefixed with do:

index.html

@@ -47,7 +47,7 @@
         <script type='text/javascript' src='js/iD/actions/actions.js'></script>
         <script type='text/javascript' src='js/iD/actions/operations.js'></script>
 
-        <script type='text/javascript' src='js/iD/controller/controller.js'></script>
+        <script type='text/javascript' src='js/iD/controller/Controller.js'></script>
 
         <script type='text/javascript' src='js/iD/format/format.js'></script>
         <script type='text/javascript' src='js/iD/format/GeoJSON.js'></script>
@@ -74,7 +74,7 @@
             iD.Hash().map(map);
             iD.UI.bind();
 
-            var controller = iD.controller(map);
+            var controller = iD.Controller(map);
 
             d3.selectAll('button#place').on('click', function() {
                 controller.go(iD.actions.AddPlace);

js/iD/controller/controller.js

@@ -1,6 +1,6 @@
 // A controller holds a single action at a time and calls `.enter` and `.exit`
 // to bind and unbind actions.
-iD.controller = function(map) {
+iD.Controller = function(map) {
     var controller = { action: null };
 
     controller.go = function(x) {

js/iD/graph/Graph.js

@@ -1,4 +1,5 @@
 iD.Graph = function(entities, annotation) {
+    if (!(this instanceof iD.Graph)) return new iD.Graph(entities, annotation)
     this.entities = entities || {};
     this.annotation = annotation;
 };
@@ -36,11 +37,11 @@ iD.Graph.prototype = {
     replace: function(entity, annotation) {
         var o = {};
         o[entity.id] = entity;
-        return new iD.Graph(pdata.object(this.entities).set(o).get(), annotation);
+        return iD.Graph(pdata.object(this.entities).set(o).get(), annotation);
     },
 
     remove: function(entity, annotation) {
-        return new iD.Graph(pdata.object(this.entities).remove(entity.id).get(), annotation);
+        return iD.Graph(pdata.object(this.entities).remove(entity.id).get(), annotation);
     },
 
     // get all objects that intersect an extent.

js/iD/graph/History.js

@@ -1,5 +1,6 @@
 iD.History = function() {
-    this.stack = [new iD.Graph()];
+    if (!(this instanceof iD.History)) return new iD.History();
+    this.stack = [iD.Graph()];
     this.index = 0;
 };
 

js/iD/renderer/Map.js

@@ -22,8 +22,8 @@ iD.Map = function(elem) {
         width, height,
         dispatch = d3.dispatch('move', 'update'),
         // data
-        history = new iD.History(),
-        connection = new iD.Connection(history.graph()),
+        history = iD.History(),
+        connection = iD.Connection(history.graph()),
         inspector = iD.Inspector(history),
         parent = d3.select(elem),
         selection = [],