Serialize before deserialize when configuring attrs. Fixes #3433.

src/micro/attributes.html

@@ -193,7 +193,7 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
           break;
 
         case Boolean:
-          value = (value !== null);
+          value = (value != null);
           break;
 
         case Object:

src/standard/configure.html

@@ -116,7 +116,7 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
     _configureProperties: function(properties, config) {
       for (var i in properties) {
         var c = properties[i];
-        // Allow properties set before upgrade on the instance 
+        // Allow properties set before upgrade on the instance
         // to override default values. This allows late upgrade + an early set
         // to not b0rk accessors on the prototype.
         // Perf testing has shown `hasOwnProperty` to be ok here.
@@ -153,7 +153,7 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
                   var value = (p === x.effect.value) ? config[p] :
                     this._get(x.effect.value, config);
                   if (x.effect.kind == 'attribute') {
-                    value = node.deserialize(value,
+                    value = node.deserialize(node.serialize(value),
                       node._propertyInfo[name].type);
                   }
                   node._configValue(name, value);

test/unit/configure-elements.html

@@ -128,12 +128,18 @@
           type: Number,
           observer: 'attrNumberChanged',
           value: 0
+        },
+        attrBoolean: {
+          type: Boolean,
+          observer: 'attrBooleanChanged',
+          // value: true
         }
       },
 
       created: function() {
         this.attrDashChanged = sinon.spy();
         this.attrNumberChanged = sinon.spy();
+        this.attrBooleanChanged = sinon.spy();
       }
 
     });
@@ -142,7 +148,7 @@
 
 <dom-module id="x-configure-host">
   <template>
-    <x-configure-child id="child" content="{{content}}" object="{{object.goo}}" attr$="{{attrValue}}" attr-dash$="{{attrValue}}" attr-number$="{{attrNumber}}"></x-configure-child>
+    <x-configure-child id="child" content="{{content}}" object="{{object.goo}}" attr$="{{attrValue}}" attr-dash$="{{attrValue}}" attr-number$="{{attrNumber}}" attr-boolean$="{{attrBoolean}}"></x-configure-child>
   </template>
   <script>
     Polymer({
@@ -175,7 +181,10 @@
           value: 'attrValue'
         },
         attrNumber: {
-          value: '42'
+          value: 42
+        },
+        attrBoolean: {
+          value: false
         }
       }
 

test/unit/configure.html

@@ -100,7 +100,13 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
       assert.notProperty(e.$.child, 'attr-number');
       assert.strictEqual(e.$.child.attrNumber, 42);
       assert.isTrue(e.$.child.attrNumberChanged.calledOnce);
-      assert.equal(e.$.child.attrNumberChanged.getCall(0).args[0], 42);
+      assert.strictEqual(e.$.child.attrNumberChanged.getCall(0).args[0], 42);
+
+      assert.equal(e.$.child.hasAttribute('attr-boolean'), false);
+      assert.notProperty(e.$.child, 'attr-boolean');
+      assert.strictEqual(e.$.child.attrBoolean, false);
+      assert.isTrue(e.$.child.attrBooleanChanged.calledOnce);
+      assert.strictEqual(e.$.child.attrBooleanChanged.getCall(0).args[0], false);
     });
 
     test('pre-register property assignment does not break getters and setters', function() {