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/Tile/Image.js

@@ -589,7 +589,7 @@ OpenLayers.Tile.Image = OpenLayers.Class(OpenLayers.Tile, {
         // before continuing execution.
         if (OpenLayers.Util.indexOf(this.layer.SUPPORTED_TRANSITIONS, 
                 this.layer.transitionEffect) != -1) {
-            if (navigator.userAgent.toLowerCase().indexOf("gecko") != -1) { 
+            if (OpenLayers.IS_GECKO === true) { 
                 this.frame.scrollLeft = this.frame.scrollLeft; 
             } 
         }
@@ -608,5 +608,5 @@ OpenLayers.Tile.Image = OpenLayers.Class(OpenLayers.Tile, {
 );
 
 OpenLayers.Tile.Image.useBlankTile = ( 
-    OpenLayers.Util.getBrowserName() == "safari" || 
-    OpenLayers.Util.getBrowserName() == "opera"); 
+    OpenLayers.BROWSER_NAME == "safari" || 
+    OpenLayers.BROWSER_NAME == "opera"); 

lib/OpenLayers/Tile/Image/IFrame.js

@@ -84,7 +84,7 @@ OpenLayers.Tile.Image.IFrame = {
             if (this.imgDiv == null) {
                 var eventPane = document.createElement("div");
 
-                if(OpenLayers.Util.getBrowserName() == "msie") {
+                if(OpenLayers.BROWSER_NAME == "msie") {
                     // IE cannot handle events on elements without backgroundcolor.
                     // So we use this little hack to make elements transparent
                     eventPane.style.backgroundColor = '#FFFFFF';
@@ -131,7 +131,7 @@ OpenLayers.Tile.Image.IFrame = {
     createIFrame: function() {
         var id = this.id+'_iFrame';
         var iframe;
-        if(OpenLayers.Util.getBrowserName() == "msie") {
+        if(OpenLayers.BROWSER_NAME == "msie") {
             // InternetExplorer does not set the name attribute of an iFrame 
             // properly via DOM manipulation, so we need to do it on our own with
             // this hack.