Highlight polygon

HTML

<link rel="stylesheet" href="http://cdn.leafletjs.com/leaflet-0.7.3/leaflet.css">
<script src="http://cdn.leafletjs.com/leaflet-0.7.3/leaflet-src.js"></script>
<div id="map" ></div>

CSS

#map {
    height: 400px;
}

JavaScript

// credits: https://github.com/turban/Leaflet.Mask
L.Mask = L.Polygon.extend({
	options: {
		stroke: false,
		color: '#333',
		fillOpacity: 0.5,
		clickable: true,

		outerBounds: new L.LatLngBounds([-90, -360], [90, 360])
	},

	initialize: function (latLngs, options) {
        
         var outerBoundsLatLngs = [
			this.options.outerBounds.getSouthWest(),
			this.options.outerBounds.getNorthWest(),
			this.options.outerBounds.getNorthEast(),
			this.options.outerBounds.getSouthEast()
		];
        L.Polygon.prototype.initialize.call(this, [outerBoundsLatLngs, latLngs], options);	
	},

});
L.mask = function (latLngs, options) {
	return new L.Mask(latLngs, options);
};



// Polygon created with http://geojson.io/
var Island = {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [
              2.548828125,
              51.055207338584964
            ],
            [
              1.6259765625,
              50.84757295365389
            ],
            [
              1.5380859375,
              50.078294547389426
            ],
            [
              0.2197265625,
              49.696061819115634
            ],
            [
              -0.59326171875,
              49.33944093715546
            ],
            [
              -1.2744140625,
              49.63917719651036
            ],
            [
              -1.9335937499999998,
              49.681846899401286
            ],
            [
              -1.3842773437499998,
              48.58932584966972
            ],
            [
              -2.3291015625,
              48.61838518688487
            ],
            [
              -3.18603515625,
              48.8936153614802
            ],
            [
              -4.658203125,
              48.66194284607008
            ],
            [
              -4.8779296875,
             ...