Using compiled regexp to replace dots.

Though split and join appear to be more efficient in Chrome, a compiled regexp looks to be a safer bet across the board.  See http://jsperf.com/dotless (and http://jsperf.com/dotless-nop for the NOP).

lib/OpenLayers/Util.js

@@ -130,6 +130,17 @@ OpenLayers.Util.indexOf = function(array, obj) {
 };
 
 
+/**
+ * Property: dotless
+ * {RegExp}
+ * Compiled regular expression to match dots (".").  This is used for replacing
+ *     dots in identifiers.  Because object identifiers are frequently used for
+ *     DOM element identifiers by the library, we avoid using dots to make for
+ *     more sensible CSS selectors.
+ *
+ * TODO: Use a module pattern to avoid bloating the API with stuff like this.
+ */
+OpenLayers.Util.dotless = /\./g;
 
 /**
  * Function: modifyDOMElement
@@ -158,7 +169,7 @@ OpenLayers.Util.modifyDOMElement = function(element, id, px, sz, position,
                                             border, overflow, opacity) {
 
     if (id) {
-        element.id = id.replace(/\./g, "_");
+        element.id = id.replace(OpenLayers.Util.dotless, "_");
     }
     if (px) {
         element.style.left = px.x + "px";
@@ -939,7 +950,7 @@ OpenLayers.Util.createUniqueID = function(prefix) {
     if (prefix == null) {
         prefix = "id_";
     } else {
-        prefix = prefix.replace(/\./g, "_");
+        prefix = prefix.replace(OpenLayers.Util.dotless, "_");
     }
     OpenLayers.Util.lastSeqID += 1; 
     return prefix + OpenLayers.Util.lastSeqID;