Import Polymer 0.8 and several key elements.

third_party/polymer/v0_8/components-chromium/polymer/src/micro/mixins-extracted.js

Index: third_party/polymer/v0_8/components-chromium/polymer/src/micro/mixins-extracted.js
diff --git a/third_party/polymer/v0_8/components-chromium/polymer/src/micro/mixins-extracted.js b/third_party/polymer/v0_8/components-chromium/polymer/src/micro/mixins-extracted.js
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@@ -0,0 +1,30 @@
+
+
+  /**
+   * Automatically extend using objects referenced in `mixins` array. 
+   * 
+   *     Polymer({
+   *     
+   *       mixins: [
+   *         someMixinObject
+   *       ]
+   *     
+   *       ...
+   *     
+   *     });
+   * 
+   * @class base feature: mixins
+   */
+
+  Polymer.Base._addFeature({
+
+    _prepMixins: function() {
+      if (this.mixins) {
+        this.mixins.forEach(function(m) {
+          Polymer.Base.extend(this, m);
+        }, this);
+      }
+    }
+
+  });
+