Merge "Fix parse error when opacity is set to zero to alpha() function"

Author: jenkins-bot

lib/Less/Parser.php

@@ -2134,7 +2134,7 @@ private function parseAlpha() {
 		}
 
 		$value = $this->matchReg( '/\\G[0-9]+/' );
-		if ( !$value ) {
+		if ( $value === null ) {
 			$value = $this->expect( 'parseEntitiesVariable', 'Could not parse alpha' );
 		}
 

test/Fixtures/less.php/css/T371606-alpha-zero-error.css

@@ -0,0 +1,3 @@
+.alpha {
+  filter: alpha(opacity=0);
+}

test/Fixtures/less.php/less/T371606-alpha-zero-error.less

@@ -0,0 +1,3 @@
+.alpha {
+	filter: alpha(opacity=0);
+  }