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/Util.js

@@ -1540,6 +1540,43 @@ OpenLayers.Util.removeTail = function(url) {
     return head;
 };
 
+/**
+ * Constant: IS_GECKO
+ * {Boolean} True if the userAgent reports the browser to use the Gecko engine
+ */
+OpenLayers.IS_GECKO = (function() {
+    return navigator.userAgent.toLowerCase().indexOf("gecko") != -1;
+})();
+
+/**
+ * Constant: BROWSER_NAME
+ * {String}
+ * A substring of the navigator.userAgent property.  Depending on the userAgent
+ *     property, this will be the empty string or one of the following:
+ *     * "opera" -- Opera
+ *     * "msie"  -- Internet Explorer
+ *     * "safari" -- Safari
+ *     * "firefox" -- FireFox
+ *     * "mozilla" -- Mozilla
+ */
+OpenLayers.BROWSER_NAME = (function() {
+    var name = "";
+    var ua = navigator.userAgent.toLowerCase();
+    if (ua.indexOf("opera") != -1) {
+        name = "opera";
+    } else if (ua.indexOf("msie") != -1) {
+        name = "msie";
+    } else if (ua.indexOf("safari") != -1) {
+        name = "safari";
+    } else if (ua.indexOf("mozilla") != -1) {
+        if (ua.indexOf("firefox") != -1) {
+            name = "firefox";
+        } else {
+            name = "mozilla";
+        }
+    }
+    return name;
+})();
 
 /**
  * Function: getBrowserName
@@ -1559,29 +1596,9 @@ OpenLayers.Util.removeTail = function(url) {
  *           return an empty string.
  */
 OpenLayers.Util.getBrowserName = function() {
-    var browserName = "";
-    
-    var ua = navigator.userAgent.toLowerCase();
-    if ( ua.indexOf( "opera" ) != -1 ) {
-        browserName = "opera";
-    } else if ( ua.indexOf( "msie" ) != -1 ) {
-        browserName = "msie";
-    } else if ( ua.indexOf( "safari" ) != -1 ) {
-        browserName = "safari";
-    } else if ( ua.indexOf( "mozilla" ) != -1 ) {
-        if ( ua.indexOf( "firefox" ) != -1 ) {
-            browserName = "firefox";
-        } else {
-            browserName = "mozilla";
-        }
-    }
-    
-    return browserName;
+    return OpenLayers.BROWSER_NAME;
 };
 
-
-
-    
 /**
  * Method: getRenderedDimensions
  * Renders the contentHTML offscreen to determine actual dimensions for