Avoiding unnecessary repeated checks of navigator.userAgent. The constants added here should not be used outside the library. In the future, they should be removed from the library. r=ahocevar (closes #2911)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@10868 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Vector.js

@@ -476,7 +476,7 @@ OpenLayers.Layer.Vector = OpenLayers.Class(OpenLayers.Layer, {
             // Force a reflow on gecko based browsers to prevent jump/flicker.
             // This seems to happen on only certain configurations; it was originally
             // noticed in FF 2.0 and Linux.
-            if (navigator.userAgent.toLowerCase().indexOf("gecko") != -1) {
+            if (OpenLayers.IS_GECKO === true) {
                 this.div.scrollLeft = this.div.scrollLeft;
             }