fix "file" in the source map

diff --git a/bin/uglifyjs2 b/bin/uglifyjs2
index 1b64c2f..0c2de4e 100755 (executable)
--- a/bin/uglifyjs2
+++ b/bin/uglifyjs2
@@ -61,7 +61,7 @@ var STATS = {};
 var OUTPUT_FILE = ARGS.o;
 
 var SOURCE_MAP = ARGS.source_map ? UglifyJS.SourceMap({
-    file: output,
+    file: OUTPUT_FILE,
     root: ARGS.source_map_root
 }) : null;