paragraph breaks get removed when generating emails

[dbaron]

Describe the bug
When I generate intent (to ship) emails using Chromestatus, for at least some fields the paragraph breaks / line breaks in the field get removed when the intent email is generated. The loss of the paragraph breaks makes the email confusing.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://chromestatus.com/feature/5112013093339136
2. Use the UI to draft the intent to ship email.

Expected behavior
The compatibility section begins with the text:

There's some interoperability and compatibility risk around changes to <details> styling.

Currently styling of the list marker is not interoperable as there are two different approaches, one taken by Gecko and (current) Chromium, and another taken by WebKit (which was previously shared with Chromium). However, this initial phase of work doesn't address marker styling very much.

In most cases, the changes being proposed here are compatible with existing content. However, they do include one breaking change, in that they make the <slot> matched by the ::details-content pseudo-element be display:block by default rather than being display:block when closed and display:contents when open. This could potentially break content that is currently using display:contents on the details element, although such content is likely rare, and could be easily fixed by explicitly setting the old style (details[open]::details-content { display: contents }). This change is included because it significantly improves the developer ergonomics of using ::details-content; however, if it turns out to cause compatibility issues then it could be rolled back (at the cost of developer ergonomics for users of ::details-content, some of which who would need to explicitly specify display to override the display:contents default). For more details, see https://crrev.com/c/5594192 .

(Instead, all of that text ends up as a single paragraph as seen in the intent. Note that I did add an additional paragraph after it when editing the intent message, but I forgot to readd the paragraph breaks in the middle.)