wx.loadFontFace({
  family: 'Bitstream Vera Serif Bold',
  source: 'url("https://developer.mozilla.org/@api/deki/files/2934/=VeraSeBd.ttf")',
  success: function(res) {    console.log(res.status) //  loaded
  },
  fail: function(res) {    console.log(res.status) //  error
  },
  complete: function(res) {    console.log(res.status);
  }
});

调用这个方法报错：wx.loadFontFace is not a function;