Revert "Move the popup close box sizing to CSS"

Moving the box size to CSS broke `Popup.setSize()`; the function
expects a width for the padding computation. Because this function is
called before the div is added to the DOM, the size can't be
computed.

This reverts commit 134f24480a.

lib/OpenLayers/Popup.js

@@ -872,11 +872,13 @@ OpenLayers.Popup = OpenLayers.Class({
      */
     addCloseBox: function(callback) {
 
-        this.closeDiv = OpenLayers.Util.createDiv(this.id + "_close");
+        this.closeDiv = OpenLayers.Util.createDiv(
+            this.id + "_close", null, {w: 17, h: 17}
+        );
         this.closeDiv.className = "olPopupCloseBox"; 
         
         // use the content div's css padding to determine if we should
-        //  pad the close div
+        //  padd the close div
         var contentDivPadding = this.getContentDivPadding();
          
         this.closeDiv.style.right = contentDivPadding.right + "px";