Add support for using JsBarcode in implementations that don't impleme…

…nt measureText.

bin/renderers/shared.js

@@ -76,13 +76,20 @@ function messureText(string, options, context) {
 	} else if (typeof document !== "undefined") {
 		ctx = document.createElement("canvas").getContext("2d");
 	} else {
-		// If the text cannot be messured we will return 0.
+		// If the text cannot be measured we will return 0.
 		// This will make some barcode with big text render incorrectly
 		return 0;
 	}
 	ctx.font = options.fontOptions + " " + options.fontSize + "px " + options.font;
 
 	// Calculate the width of the encoding
+	var measureTextResult = ctx.measureText(string);
+	if (!measureTextResult) {
+		// Some implementations don't implement measureText and return undefined.
+		// If the text cannot be measured we will return 0.
+		// This will make some barcode with big text render incorrectly
+		return 0;
+	}
 	var size = ctx.measureText(string).width;
 
 	return size;