NaN is invalid a compute time, so OK at parsing time, maybe add a warning?

This should fix #469

Author: ylafon

org/w3c/css/values/CssNumber.java

@@ -86,7 +86,7 @@ public void set(String s, ApplContext ac)
                 _strval = "e";
                 break;
             case "infinity":
-                value = BigDecimal.valueOf(Double.POSITIVE_INFINITY);
+                value = BigDecimal.valueOf(Double.MAX_VALUE);
                 isInt = true;
                 _strval = "infinity";
                 break;
@@ -109,6 +109,12 @@ public void set(String s, ApplContext ac)
                 isInt = true;
                 _strval = val.toLowerCase();
                 break;
+            case "nan":
+                // FIXME add warning that this iss invalid at compute time?
+                value = BigDecimal.valueOf(Long.MAX_VALUE);
+                isInt = false;
+                _strval = "NaN";
+                break;
             default:
                 value = new BigDecimal(val);
                 isInt = (val.indexOf('.') < 0);