ConversationWebView: Fix plain text emails sometimes being too wide
Using `whitespace: pre-wrap` to format plain text email sometimes causes additional width to be allocated by the plain text blocks that then does not get used due to the constraints on the HTML element. The allocated space remains however and hence an un-needed horizontal scrollbar appears. Using `break-spaces` instead seems to help since it allows breaks after a space character, leading to the additional space not otherwise being allocated.
mjog/283-plain-text-whitespace-fixes in 14 minutes and 4 seconds (queued for 1 second)7 jobs for