fixed 'sizeToFill' and added test

test/test.js

@@ -0,0 +1,29 @@
+var CanvasTextWrapper = require('../CanvasTextWrapper').CanvasTextWrapper;
+
+var body = document.getElementsByTagName('body')[0];
+body.style.margin = 0;
+
+var canvas = document.createElement('canvas');
+canvas.width = 600;
+canvas.height = 600;
+canvas.style.position = 'absolute';
+canvas.style.left = '50%';
+canvas.style.top = '50%';
+canvas.style.transform = 'translateX(-50%) translateY(-50%)';
+
+body.appendChild(canvas);
+
+var ctx = canvas.getContext('2d');
+var gradient = ctx.createLinearGradient(0, 0, canvas.width, 0);
+gradient.addColorStop('0.2', 'magenta');
+gradient.addColorStop('0.5', 'blue');
+gradient.addColorStop('0.7', 'purple');
+ctx.fillStyle = gradient;
+
+var opts = {
+	sizeToFill: true,
+	textAlign: 'center',
+	verticalAlign: 'middle'
+};
+
+CanvasTextWrapper(canvas, 'What an awesome library!', opts);