Unable to preview image or PDF file in JIRA

Summary

Unable to preview image or PDF file in JIRA preview in Issue View.

Environment

• Reproducible in 7.12.1 and 7.12.0
• Unable to reproduce with 7.11.1 and 7.7.0.
• Affecting only Internet Explorer 11.

Steps to Reproduce

1. Setup a JIRA 7.12.1.
2. Create a new project and raise a new issue.
3. Upload an image and a PDF file.
4. Click on them to preview after the upload is done.

Expected Results

The previewer able to show the image and PDF file in the preview box.

Actual Results

• The preview shows only 'loading' icon and it will sometimes cause the entire IE11 to hang.
• In the browser console, you will see the following:
  

Workaround

1. Please use other web browsers such as Google Chrome.
2. Open it as a new tab in IE11.