UserAgent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:56.0) Gecko/20100101 Firefox/56.0

Steps to reproduce the problem:
1. Set the placeholder of a textarea to a value including \r via JS/Include 
 in the source of a textarea placeholder
2. Observe that they aren't rendered as line breaks in the placeholder

What is the expected behavior?
textarea placeholders should render CRs as line breaks in all instances.

What went wrong?
When the HTML source for a placeholder includes explicit CRs via entities, or when a placeholder is set via JS containing \r, line breaks aren't rendered.

Did this work before? No 

Does this work in other browsers? No
 There are three scenarios to test: CR in the source, CR as an entity (
) in the source, and setting a value via JS with a CR as \r in the string.
Chrome line breaks on all three in textarea content, but only on CR in the source for the placeholder.

Firefox is currently worse since it doesn't support newlines in textarea placeholders at all, but that is in the process of being fixed, and it was while doing so and writing web platform tests for it that this behaviour came to light.  It line breaks for all three scenarios in textarea content.
https://bugzilla.mozilla.org/show_bug.cgi?id=1391044

Edge does the same as Chrome for placeholders, but extends that behaviour to the content of the textarea as well (only CR in source), so is at least the most consistent of the three between placeholder and content, but the worst in terms of the spec.

Chrome version: 62.0.3202.94 (Official Build) Built on Ubuntu , running on Ubuntu 17.04 (64-bit)  Channel: n/a
OS Version: 
Flash Version: 

https://html.spec.whatwg.org/multipage/form-elements.html#attr-textarea-placeholder
"All U+000D CARRIAGE RETURN U+000A LINE FEED character pairs (CRLF) in the hint, as well as all other U+000D CARRIAGE RETURN (CR) and U+000A LINE FEED (LF) characters in the hint, must be treated as line breaks when rendering the hint.
 

Deleted: ta-ph-cr.html 856 bytes

ta-ph-cr.html 856 bytes View Download