Make camelcasing use a regular expression for CSS properties.

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 9fd94afccb91fa101e004f895bb498851fe1524c..6f4577128c902e9c065c1fff9a8f306017769442 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -2824,18 +2824,10 @@ class CssRule extends Interceptor {
   }
 
   String _camelCase(String hyphenated) {
-    bool firstWord = true;
-    return hyphenated.splitMapJoin('-', onMatch : (_) => '',
-        onNonMatch : (String word) {
-      if (word.length > 0) {
-        if (firstWord) {
-          firstWord = false;
-          return word;
-        }
-        return word[0].toUpperCase() + word.substring(1);
-      }
-      return '';
-    });
+    // The "ms" prefix is always lowercased.
+    return hyphenated.replaceFirst(new RegExp('^-ms-'), 'ms-').replaceAllMapped(
+        new RegExp('-([a-z]+)', caseSensitive: false),
+        (match) => match[0][1].toUpperCase() + match[0].substring(2));
   }
 
   void _setPropertyHelper(String propertyName, String value, [String priority]) {