Hide empty image displayed as broken image

issue7319
review47281002

src/common.js

@@ -2525,7 +2525,7 @@
         },
         register_icon: function(icon_name) {
             if (!icon_name) {
-                return jQuery.Deferred().reject();
+                return jQuery.when();
             } else if ((icon_name in this.loaded_icons) ||
                     ~Sao.common.LOCAL_ICONS.indexOf(icon_name)) {
                 return jQuery.when(this.get_icon_url(icon_name));

src/sao.less

@@ -94,6 +94,11 @@ input[type='color'] {
     }
 }
 
+/* Hide empty image displayed as broken image */
+[src=''] {
+    visibility: hidden;
+}
+
 img.icon {
     height: unit(@line-height-base, em);
 }

src/view/tree.js

@@ -1540,7 +1540,7 @@
                         } else {
                             img_tag = cell;
                         }
-                        img_tag.attr('src', url);
+                        img_tag.attr('src', url || '');
                     }.bind(this));
                 } else {
                     value = this.attributes.string || '';