In this step, you download Dart and get the sample code.
→ If you haven’t already done so, get the Dart download by clicking the big Download Dart + Editor button on the Dart homepage.
→ Unzip the ZIP file, which creates a directory called dart.
→ Go to the dart directory and double-click DartEditor.
Got questions? Having trouble? Go to the Troubleshooting Dart Editor page.
→ Unzip the ZIP file.
You should now have a directory called risk-polymer-codelab-master.