MDL-83614 javascript: apply icon class to legacy lightbox spinner.

lib/javascript-static.js

@@ -800,14 +800,10 @@ M.util.add_lightbox = function(Y, node) {
     }
 
     node.setStyle('position', 'relative');
+
     var waiticon = Y.Node.create('<img />')
-    .setAttrs({
-        'src' : M.util.image_url(WAITICON.pix, WAITICON.component)
-    })
-    .setStyles({
-        'position' : 'relative',
-        'top' : '50%'
-    });
+        .setAttribute('src', M.util.image_url(WAITICON.pix, WAITICON.component))
+        .addClass('icon');
 
     var lightbox = Y.Node.create('<div></div>')
     .setStyles({
@@ -817,6 +813,7 @@ M.util.add_lightbox = function(Y, node) {
         'height' : '100%',
         'top' : 0,
         'left' : 0,
+        'paddingTop': '50%',
         'backgroundColor' : 'white',
         'textAlign' : 'center'
     })