fix isAbsolute for windows fs paths

Author: SmetDenis

src/Url.php

@@ -521,7 +521,8 @@ public static function pathToUrl($path)
      */
     public static function isAbsolute($path)
     {
-        $result = preg_match('#^(?:[a-z-]+:|\/\/)#i', $path);
+        $result = strpos($path, '//') === 0
+            || preg_match('#^[a-z-]{3,}:\/\/#i', $path);
 
         return $result;
     }

tests/UrlTest.php

@@ -172,7 +172,12 @@ public function testIsAbsolute()
         isTrue(Url::isAbsolute('https://site.com'));
         isTrue(Url::isAbsolute('http://site.com'));
         isTrue(Url::isAbsolute('//site.com'));
+        isTrue(Url::isAbsolute('ftp://site.com'));
+
         isFalse(Url::isAbsolute('/path/to/file'));
+        isFalse(Url::isAbsolute('w:/path/to/file'));
+        isFalse(Url::isAbsolute('W:/path/to/file'));
+        isFalse(Url::isAbsolute('W:\path\to\file'));
     }
 
     public function testEmpty()