Fix #12886. Fix map file reference in .min.js file.

Cherry picked from e348b406 .

Gruntfile.js

@@ -432,11 +432,14 @@ module.exports = function( grunt ) {
 				nonascii = true;
 			}
 
-			// Modify map so that it points to files in the same folder;
+			// Modify map/min so that it points to files in the same folder;
 			// see https://github.com/mishoo/UglifyJS2/issues/47
 			if ( /\.map$/.test( filename ) ) {
 				text = text.replace( /"dist\//g, "\"" );
 				fs.writeFileSync( filename, text, "utf-8" );
+			} else if ( /\.min\.js$/.test( filename ) ) {
+				text = text.replace( /sourceMappingURL=dist\//, "sourceMappingURL=" );
+				fs.writeFileSync( filename, text, "utf-8" );
 			}
 
 			// Optionally copy dist files to other locations