allow defaulting property values by having property getter default to value stored on prototype (if there is no matching attribute)

src/g-component.html

@@ -38,7 +38,8 @@ license that can be found in the LICENSE file.
           a = a.trim();
           Object.defineProperty(this, a, {
             get: function() {
-              return this.getAttribute(a);
+              return this.hasAttribute(a) ? this.getAttribute(a) :
+                this.__proto__[a];
             },
             set: function(v) {
               return this.setAttribute(a, v);