Support improper code fencing

[Mottie]

Please add support for the following example. It wraps the code in a single backtick, but because it includes a line break (two, or more, carriage returns), the markdown renderer ignores the block.

Here is an example:

`// The space below is the cause of this problem

document.addEventListener("input", function (event) {
if (event.target.id === "test") {
// do something
} else {
// do something else
}
});`