Add rendering for tag-crossing pedestrian crosswalks

css/map.css

@@ -893,6 +893,14 @@ path.stroke.tag-highway-footway {
     stroke: #ae8681;
 }
 
+.preset-icon .icon.highway-footway.tag-crossing {
+    color: #444;
+}
+path.stroke.tag-highway-footway.tag-crossing {
+    stroke: #444;
+    stroke-dasharray: 6, 4;
+}
+
 .preset-icon .icon.tag-route-bicycle,
 .preset-icon .icon.highway-cycleway {
     color: #58a9ed;

js/id/svg/tag_classes.js

@@ -10,7 +10,7 @@ iD.svg.TagClasses = function() {
         ],
         secondaries = [
             'oneway', 'bridge', 'tunnel', 'embankment', 'cutting', 'barrier',
-            'surface', 'tracktype'
+            'surface', 'tracktype', 'crossing'
         ],
         tagClassRe = /^tag-/,
         tags = function(entity) { return entity.tags; };