stringify: do not use unescapedIndexOf in property parameters

… as \ is no escape character there.  When the propery parameter
contains :, then it must be quoted, the colon cannot be escaped.

As the function stringify.propertyValue in fact stringifies
property parameter values, it is renamed accordingly.

kewisch#535

lib/ical/stringify.js

@@ -143,7 +143,7 @@ ICAL.stringify = (function() {
 
 
         line += ';' + paramName.toUpperCase();
-        line += '=' + stringify.propertyValue(value);
+        line += '=' + stringify.propertyParameterValue(value);
       }
     }
 
@@ -214,22 +214,21 @@ ICAL.stringify = (function() {
   };
 
   /**
-   * Handles escaping of property values that may contain:
+   * Handles escaping of property parameter values that may contain:
    *
    *    COLON (:), SEMICOLON (;), or COMMA (,)
    *
    * If any of the above are present the result is wrapped
    * in double quotes.
    *
-   * @function ICAL.stringify.propertyValue
+   * @function ICAL.stringify.propertyParameterValue
    * @param {String} value      Raw property value
    * @return {String}           Given or escaped value when needed
    */
-  stringify.propertyValue = function(value) {
-
-    if ((helpers.unescapedIndexOf(value, ',') === -1) &&
-        (helpers.unescapedIndexOf(value, ':') === -1) &&
-        (helpers.unescapedIndexOf(value, ';') === -1)) {
+  stringify.propertyParameterValue = function(value) {
+    if ((value.indexOf(',') === -1) &&
+        (value.indexOf(':') === -1) &&
+        (value.indexOf(';') === -1)) {
 
       return value;
     }

test/stringify_test.js

@@ -87,6 +87,13 @@ suite('ICAL.stringify', function() {
       delete ICAL.design.defaultSet.property.custom;
     });
 
+    test('stringify property value containing "escaped" ; , :', function() {
+      var subject = new ICAL.Property('attendee');
+      subject.setParameter('cn', 'X\\:');
+      subject.setValue('mailto:id');
+      assert.equal(subject.toICALString(), 'ATTENDEE;CN="X\\:":mailto:id');
+    });
+
     test('rfc6868 roundtrip', function() {
       var subject = new ICAL.Property('attendee');
       var input = "caret ^ dquote \" newline \n end";