Unable to load custom font

## Issue or Feature

## Steps to Reproduc
```

## Your Environment
* Version of node-canvas (output of `npm list canvas` or `yarn list canvas`):
* Environment (e.g. node 4.2.0 on Mac OS X 10.8):

const { createCanvas, Image, registerFont } = require('canvas');
const Canvas=require('canvas');
var fs = require('fs')
var path = require('path')
const express = require('express');
const app = express();
app.get('/font/:font', async function (req, res) {
Canvas.registerFont('./font/NotoSansHans-Bold.ttf', { family: 'Noto Sans S Chinese Bold' })
const canvas = createCanvas(400, 400)
const ctx = canvas.getContext('2d')
const font=req.params.font;
ctx.font = "280px Noto Sans S Chinese Bold"
ctx.fillStyle="#fff"
ctx.fillText((font), 70, 400-100)
console.log(font)
let out=fs.createWriteStream(path.join(__dirname, "/i/"+font+'.png'))
canvas.createPNGStream().pipe(out)
out.on('finish', () => {
res.end('make ok')
console.log('The PNG file was created.')
})
});
app.listen(3200, function () {
console.log('Example app listening on port 3200!');
});

$ node test.js
Example app listening on port 3200!

(process:5400): Pango-WARNING **: 14:49:53.166: couldn't load font "Noto Sans S
Chinese Bold Not-Rotated 280px", falling back to "Sans Bold Not-Rotated 280px",
expect ugly output.
我
The PNG file was created.