message: [web-component-decorators] Only notify once the constructor is finished.
diff: @@ -172,12 +172,12 @@ class DecoratorData {
  attrData.instanceValueMap.set(this, newValue);
  if (decoratorData._isInstanceConstructed(this)) {
  this[decoratorData.superSetAttributeSymbol].call(this, attrData.attributeName, newValue);
  - }
  // Notify observers
  for (const methodName of attrData.observers) {
  this[methodName].call(this, jsName);
  }
  + }
  };
  if (delete this._elementProto[jsName]) {
  