Enforce token syntax for CssClassSet arguments

sdk/lib/html/html_common/css_class_set.dart

Index: sdk/lib/html/html_common/css_class_set.dart
diff --git a/sdk/lib/html/html_common/css_class_set.dart b/sdk/lib/html/html_common/css_class_set.dart
index 0380d2d82e21e977a15da7c8731f5ecc337b6400..9c4b4430c0c0f59ccf92bdf2d9a941d16943b6a3 100644
--- a/sdk/lib/html/html_common/css_class_set.dart
+++ b/sdk/lib/html/html_common/css_class_set.dart
@@ -6,6 +6,13 @@ part of html_common;
 
 abstract class CssClassSetImpl implements CssClassSet {
 
+  static final RegExp _validTokenRE = new RegExp(r'^\S+$');
+
+  String _validateToken(String value) {
+    if (_validTokenRE.hasMatch(value)) return value;
+    throw new ArgumentError.value(value, 'value', 'Not a valid class token');
+  }
+
   String toString() {
     return readClasses().join(' ');
   }
@@ -18,6 +25,7 @@ abstract class CssClassSetImpl implements CssClassSet {
    * [shouldAdd] is false then we always remove [value] from the element.
    */
   bool toggle(String value, [bool shouldAdd]) {
+    _validateToken(value);
     Set<String> s = readClasses();
     bool result = false;
     if (shouldAdd == null) shouldAdd = !s.contains(value);
@@ -81,7 +89,11 @@ abstract class CssClassSetImpl implements CssClassSet {
    * This is the Dart equivalent of jQuery's
    * [hasClass](http://api.jquery.com/hasClass/).
    */
-  bool contains(Object value) => readClasses().contains(value);
+  bool contains(Object value) {
+    if (value is! String) return false;
+    _validateToken(value);
+    return readClasses().contains(value);
+  }
 
   /** Lookup from the Set interface. Not interesting for a String set. */
   String lookup(Object value) => contains(value) ? value : null;
@@ -93,6 +105,7 @@ abstract class CssClassSetImpl implements CssClassSet {
    * [addClass](http://api.jquery.com/addClass/).
    */
   bool add(String value) {
+    _validateToken(value);
     // TODO - figure out if we need to do any validation here
     // or if the browser natively does enough.
     return modify((s) => s.add(value));
@@ -106,6 +119,7 @@ abstract class CssClassSetImpl implements CssClassSet {
    * [removeClass](http://api.jquery.com/removeClass/).
    */
   bool remove(Object value) {
+    _validateToken(value);
     if (value is! String) return false;
     Set<String> s = readClasses();
     bool result = s.remove(value);
@@ -121,7 +135,7 @@ abstract class CssClassSetImpl implements CssClassSet {
    */
   void addAll(Iterable<String> iterable) {
     // TODO - see comment above about validation.
-    modify((s) => s.addAll(iterable));
+    modify((s) => s.addAll(iterable.map(_validateToken)));
   }
 
   /**
@@ -131,7 +145,7 @@ abstract class CssClassSetImpl implements CssClassSet {
    * [removeClass](http://api.jquery.com/removeClass/).
    */
   void removeAll(Iterable<Object> iterable) {
-    modify((s) => s.removeAll(iterable));
+    modify((s) => s.removeAll(iterable.map(_validateToken)));
   }
 
   /**