Use dom-to-image-more library in export-map

examples/export-map.js

@@ -24,15 +24,13 @@ const map = new Map({
 });
 
 document.getElementById('export-png').addEventListener('click', function() {
-  map.once('rendercomplete', function(event) {
-    const canvas = event.context.canvas;
-    if (navigator.msSaveBlob) {
-      navigator.msSaveBlob(canvas.msToBlob(), 'map.png');
-    } else {
-      canvas.toBlob(function(blob) {
-        saveAs(blob, 'map.png');
+  map.once('rendercomplete', function() {
+    domtoimage.toPng(map.getViewport())
+      .then(function(dataURL) {
+        const link = document.getElementById('image-download');
+        link.href = dataURL;
+        link.click();
       });
-    }
   });
   map.renderSync();
 });