invoke registration behavior before registering features, so behavi…

…ors can alter features, this requires calling behavior flattening as part of prototype desugaring instead of as part of behavior prep, so the flattened list is available early

src/lib/base.html

@@ -24,6 +24,8 @@
 
     // `this` context is a prototype, not an instance
     registerCallback: function() {
+      // TODO(sjmiles): perhaps this method should be called from polymer-bootstrap?
+      this._desugarBehaviors(); // abstract
       this._doBehavior('registered'); // abstract
       this._registerFeatures();  // abstract
     },

src/lib/polymer-bootstrap.html

@@ -20,12 +20,23 @@
     var userPolymer = window.Polymer;
 
     window.Polymer = function(prototype) {
-      var ctor = desugar(prototype);
-      // Polymer.Base is now chained to ctor.prototype, and for IE10 compat
+      // if input is a `class` (aka a function with a prototype), use the prototype
+      // remember that the `constructor` will never be called
+      if (typeof prototype === 'function') {
+        prototype = prototype.prototype;
+      }
+      // if there is no prototype, use a default empty object
+      if (!prototype) {
+        prototype = {};
+      }
+      // desugar the prototype and return a factory object
+      var factory = desugar(prototype);
+      // Polymer.Base is now chained to factory.prototype, and for IE10 compat
       // this may have resulted in a new prototype being created
-      prototype = ctor.prototype;
+      prototype = factory.prototype;
       // native Custom Elements treats 'undefined' extends property
       // as valued, the property must not exist to be ignored
+      // TODO(sjmiles): Custom Elements no longer has the above behavior
       var options = {
         prototype: prototype
       };
@@ -34,7 +45,7 @@
       }
       Polymer.telemetry._registrate(prototype);
       document.registerElement(prototype.is, options);
-      return ctor;
+      return factory;
     };
 
     var desugar = function(prototype) {

src/micro/behaviors.html

@@ -58,11 +58,10 @@
      */
     behaviors: [],
 
-    _prepBehaviors: function() {
+    _desugarBehaviors: function() {
       if (this.behaviors.length) {
         this.behaviors = this._flattenBehaviorsList(this.behaviors);
       }
-      this._prepAllBehaviors(this.behaviors);
     },
 
     _flattenBehaviorsList: function(behaviors) {
@@ -81,7 +80,11 @@
       return flat;
     },
 
-    _prepAllBehaviors: function(behaviors) {
+    _prepBehaviors: function() {
+      this._prepFlattenedBehaviors(this.behaviors);
+    },
+
+    _prepFlattenedBehaviors: function(behaviors) {
       // traverse the behaviors in _reverse_ order (youngest first) because
       // `_mixinBehavior` has _first property wins_ behavior, this is done
       // to optimize # of calls to `_copyOwnProperty`