Index: src/wp-includes/formatting.php
===================================================================
--- src/wp-includes/formatting.php	(revision 34079)
+++ src/wp-includes/formatting.php	(working copy)
@@ -2304,7 +2304,7 @@
 	 * @param string $img        Filename for the smiley image.
 	 * @param string $site_url   Site URL, as returned by site_url().
 	 */
-	$src_url = apply_filters( 'smilies_src', includes_url( "images/smilies/$img" ), $img, site_url() );
+	$src_url = apply_filters( 'smilies_src', includes_url( "images/smilies/$img", 'none' ), $img, site_url() );
 
 	return sprintf( '<img src="%s" alt="%s" class="wp-smiley" style="height: 1em; max-height: 1em;" />', esc_url( $src_url ), esc_attr( $smiley ) );
 }
Index: src/wp-includes/link-template.php
===================================================================
--- src/wp-includes/link-template.php	(revision 34079)
+++ src/wp-includes/link-template.php	(working copy)
@@ -3159,14 +3159,14 @@
 
 	if ( ! $scheme ) {
 		$scheme = is_ssl() ? 'https' : 'http';
-	} elseif ( $scheme === 'admin' || $scheme === 'login' || $scheme === 'login_post' || $scheme === 'rpc' ) {
+	} elseif ( in_array( $scheme, array( 'admin', 'login', 'login_post', 'rpc' ) ) ) {
 		$scheme = is_ssl() || force_ssl_admin() ? 'https' : 'http';
-	} elseif ( $scheme !== 'http' && $scheme !== 'https' && $scheme !== 'relative' ) {
+	} elseif ( ! in_array( $scheme, array( 'http', 'https', 'relative', 'none' ) ) ) {
 		$scheme = is_ssl() ? 'https' : 'http';
 	}
 
 	$url = trim( $url );
-	if ( substr( $url, 0, 2 ) === '//' )
+	if ( substr( $url, 0, 2 ) === '//' && 'none' !== $scheme )
 		$url = 'http:' . $url;
 
 	if ( 'relative' == $scheme ) {
@@ -3173,6 +3173,8 @@
 		$url = ltrim( preg_replace( '#^\w+://[^/]*#', '', $url ) );
 		if ( $url !== '' && $url[0] === '/' )
 			$url = '/' . ltrim($url , "/ \t\n\r\0\x0B" );
+	} elseif ( 'none' === $scheme ) {
+		$url = preg_replace( '#^\w+://#', '//', $url );
 	} else {
 		$url = preg_replace( '#^\w+://#', $scheme . '://', $url );
 	}
Index: tests/phpunit/tests/url.php
===================================================================
--- tests/phpunit/tests/url.php	(revision 34079)
+++ tests/phpunit/tests/url.php	(working copy)
@@ -425,4 +425,15 @@
 				call_user_func( $function, null, 'something...here' ) );
 		}
 	}
+
+	public function test_set_url_scheme_none() {
+		$home_host = parse_url( home_url(), PHP_URL_HOST );
+		$this->assertEquals( '//' . $home_host, set_url_scheme( home_url(), 'none' ) );
+
+		$site_host = parse_url( site_url(), PHP_URL_HOST );
+		$this->assertEquals( '//' . $site_host, set_url_scheme( site_url(), 'none' ) );
+
+		$schemeless_includes = '//' . $site_host . '/' . WPINC . '/';
+		$this->assertEquals( $schemeless_includes, set_url_scheme( includes_url(), 'none' ) );
+	}
 }