add a static function to make a Bounds from a Size. test included.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@531 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Util.js

@@ -490,6 +490,23 @@ OpenLayers.Bounds.fromArray = function(bbox) {
                                  parseFloat(bbox[3]));
 };
 
+/** Alternative constructor that builds a new OpenLayers.Bounds
+*    from an OpenLayers.Size
+* 
+* @constructor
+* 
+* @param {OpenLayers.Size} size
+*
+* @returns New OpenLayers.Bounds object built with top and left set to 0 and
+*           bottom right taken from the passed-in OpenLayers.Size.
+* @type OpenLayers.Bounds
+*/
+OpenLayers.Bounds.fromSize = function(size) {
+    return new OpenLayers.Bounds(0,
+                                 size.h,
+                                 size.w,
+                                 0);
+};
 /**
  * @param {String} quadrant 
  *