fix #1413 Invalid number value breaks CSS mode

demo/kitchen-sink/docs/css.css

@@ -1,6 +1,6 @@
 .text-layer {
     font-family: Monaco, "Courier New", monospace;
-    font-size: 12px;
+    font-size: 12pX;
     cursor: text;
 }
 

lib/ace/mode/_test/tokens_css.json

@@ -18,7 +18,7 @@
   ["support.type","font-size"],
   ["text",": "],
   ["constant.numeric","12"],
-  ["keyword","px"],
+  ["keyword","pX"],
   ["text",";"]
 ],[
    "ruleset",

lib/ace/tokenizer.js

@@ -58,6 +58,7 @@ var Tokenizer = function(rules) {
         var mapping = this.matchMappings[key] = {defaultToken: "text"};
         var flag = "g";
 
+        var spliterRurles = [];
         for (var i = 0; i < state.length; i++) {
             var rule = state[i];
             if (rule.defaultToken)
@@ -104,7 +105,7 @@ var Tokenizer = function(rules) {
                     adjustedregex = this.removeCapturingGroups(rule.regex);
                 }
                 if (!rule.splitRegex && typeof rule.token != "string")
-                    rule.splitRegex = this.createSplitterRegexp(rule.regex, flag);
+                    spliterRurles.push(rule); // flag will be known only at the very end
             }
 
             mapping[matchTotal] = i;
@@ -118,6 +119,10 @@ var Tokenizer = function(rules) {
             rule.__proto__ = null;
         }
         
+        spliterRurles.forEach(function(rule) {
+            rule.splitRegex = this.createSplitterRegexp(rule.regex, flag);
+        }, this);
+
         this.regExps[key] = new RegExp("(" + ruleRegExps.join(")|(") + ")|($)", flag);
     }
 };
@@ -146,6 +151,8 @@ var Tokenizer = function(rules) {
         if (!str)
             return [];
         var values = this.splitRegex.exec(str);
+        if (!values)
+            return "text";
         var tokens = [];
         var types = this.tokenArray;
         for (var i = 0, l = types.length; i < l; i++) {