Red line when using textarea with required attribute in Firefox

[kreinholt]

Description

When binding to a null variable, a red line appears above the textarea. This occurs in Firefox.

Expected outcome

No red line.

Actual outcome

Red line appears

Live Demo

http://jsbin.com/muqahekohi/edit?html,output

Steps to reproduce

Put a paper-textarea element on page. Bind its value to a null variable and set it to required. Load page in Firefox.

Browsers Affected

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

[alejost848]

I think I found the problem and it seems related to the box-shadow CSS property inside iron-autogrow-textarea. Checking inside the paper-input element I see there is a box-shadow: none; rule for the input, but that rule is missing from the textarea in iron-autogrow-textarea.

If I add the box-shadow: none; rule for the textarea in iron-autogrow-textarea the red line disappears and it works as expected.

@notwaldorf Is the box-shadow: none; rule intentionally left out in iron-autogrow-textarea or can it be added?