I was trying to debug #620 and got confused that it didn't show `//comment1`. Turns out we just fail silently if we can't print a node type. I added support for `line-suffix` and throw if we encounter a node type that we can't print.
This PR adds two things:
`--debug-print-doc` command that prints the formatted doc
```js
echo "<div><</div>" | ./bin/prettier.js --stdin --debug-print-doc
[
groupConditional(
group([
group([ "<", "div", group([ indent(2, []), softline() ]), ">" ]),
"<",
"</",
"div",
">"
]),
[
group([
group([ "<", "div", group([ indent(2, []), softline() ]), ">" ]),
"<",
"</",
"div",
">"
]),
group([
group([ "<", "div", group([ indent(2, []), softline() ]), ">" ]),
indent(2, groupBreak([ hardline(), "<" ])),
hardline(),
"</",
"div",
">"
])
]
),
";",
hardline()
];
```
The ability to view the IR in real time on the browser display:
The way it works is pretty cool, we take the doc IR and print a valid JavaScript string out of it, that we then send to prettier in order to make it look good :)
Christopher Chedeau
