Change user constructor to factoryImpl as an aid to compilation tool...

PRIMER.md

@@ -17,7 +17,7 @@ Below is a description of the current Polymer features, followed by individual f
 |---------|-------
 | [Custom element constructor](#element-constructor) | Polymer.Class({ … });
 | [Custom element registration](#register-element) | Polymer({ is: ‘...’,  … }};
-| [Bespoke constructor support](#bespoke-constructor) | constructor: function() { … }
+| [Bespoke constructor support](#bespoke-constructor) | factoryImpl: function() { … }
 | [Basic lifecycle callbacks](#basic-callbacks) | created, attached, detached, attributeChanged
 | [Native HTML element extension](#type-extension) | extends: ‘…’
 | [Configure properties](#property-config) | properties: { … }
@@ -133,7 +133,7 @@ var el2 = document.createElement('my-element');
 <a name="bespoke-constructor"></a>
 ## Bespoke constructor support
 
-While the standard `Polymer.Class()` and `Polymer()` functions return a basic constructor that can be used to instance the custom element, Polymer also supports providing a bespoke `constructor` function on the prototype that can, for example, accept arguments to configure the element.  In this case, the actual constructor returned from `Polymer` will first create an instance using `document.createElement`, then invoke the user-supplied `constructor` function with `this` bound to the element instance.
+While the standard `Polymer.Class()` and `Polymer()` functions return a basic constructor that can be used to instance the custom element, Polymer also supports providing a `factoryImpl` function on the prototype that can, for example, accept arguments to configure the element.  In this case, the actual constructor returned from `Polymer` will first create an instance using `document.createElement`, then invoke the user-supplied `factoryImpl` function with `this` bound to the element instance.
 
 Example:
 
@@ -142,7 +142,7 @@ MyElement = Polymer({
 
   is: 'my-element',
 
-  constructor: function(foo, bar) {
+  factoryImpl: function(foo, bar) {
     el.foo = foo;
     el.configureWithBar(bar);
   },

src/micro/constructor.html

@@ -40,10 +40,6 @@
     // registration-time
 
     _prepConstructor: function() {
-      // capture user-supplied `constructor`
-      if (this.hasOwnProperty('constructor')) {
-        this._userConstructor = this.constructor;
-      }
       // support both possible `createElement` signatures
       this._factoryArgs = this.extends ? [this.extends, this.is] : [this.is];
       // thunk the constructor to delegate allocation to `createElement`
@@ -63,8 +59,8 @@
 
     _factory: function(args) {
       var elt = document.createElement.apply(document, this._factoryArgs);
-      if (this._userConstructor) {
-        this._userConstructor.apply(elt, args);
+      if (this.factoryImpl) {
+        this.factoryImpl.apply(elt, args);
       }
       return elt;
     }

test/unit/micro.html

@@ -69,7 +69,7 @@
     test('custom constructor', function() {
       var MyElement2 = Polymer({
         is: 'my-element2',
-        constructor: function(title){
+        factoryImpl: function(title){
           this.title = title;
         }
       });