Change how Evolution talks to WebKitWebProcess

This happens with 3.33.90 and 3.33.91. I have Evo set to compose in plain text by default. The reproducer for me is simply to reply to a message, leave that composer (which works normally) open, and then reply to another message. The composer for the second message is messed up. It shows quoted segments with a solid line rather than > characters, it does not show any signature, and if I try to add new lines after or within a quoted section, the new lines keep the quote bar, rather than being unquoted as they should be.