#13 add a workaround for problematic style sheets causing rendering t…

…o fail in FF

spec/dom-to-image.spec.js

@@ -171,6 +171,15 @@
                     .then(done).catch(error);
             });
 
+            it('should not crash when loading external stylesheet causes error', function (done) {
+                loadTestPage('ext-css/dom-node.html', 'ext-css/style.css')
+                    .then(renderToPng)
+                    .then(function(){
+                        done();
+                    })
+                    .catch(error);
+            });
+
             function compareToControlImage(image, tolerance) {
                 assert.isTrue(imagediff.equal(image, controlImage(), tolerance), 'rendered and control images should be same');
             }

spec/resources/ext-css/dom-node.html

@@ -0,0 +1 @@
+<link href="http://fonts.googleapis.com/css?family=Open+Sans:400italic,600italic,400,600" rel="stylesheet">

spec/resources/ext-css/style.css

@@ -0,0 +1,5 @@
+#dom-node {
+    height: 100px;
+    width: 100px;
+    background-color: black;
+}

src/dom-to-image.js

@@ -518,7 +518,11 @@
             function getCssRules(styleSheets) {
                 var cssRules = [];
                 styleSheets.forEach(function (sheet) {
-                    util.asArray(sheet.cssRules || []).forEach(cssRules.push.bind(cssRules));
+                    try {
+                        util.asArray(sheet.cssRules || []).forEach(cssRules.push.bind(cssRules));
+                    } catch (e) {
+                        console.log('Error while reading CSS rules from ' + sheet.href, e.toString());
+                    }
                 });
                 return cssRules;
             }