Polymer 2.0 using bundle=true option with demo-snippet errors on IE11

[beonglee81]

Description

Using Polymer 2.0 with the following polymer.json

{
    "entrypoint": "demo/index.html",
    "builds": [{
        "bundle": true,
        "js": { "compile": true, "minify": true },
        "css": { "minify": true },
        "html": { "minify": true }
    }],
    "lint": {   
        "rules": ["polymer-2"]
    }
}

With the following in demo/index.html

      <demo-snippet>
        <template>
          <h1>simple demo</h1>
        </template>
      </demo-snippet>

Expected outcome

Actual outcome

Live Demo

Steps to reproduce

Browsers Affected

• [ ] Chrome
• [ ] Firefox
• [ ] Safari 9
• [ ] Safari 8
• [ ] Safari 7
• [ ] Edge
• [x] IE 11
• [ ] IE 10