fix corner case in `ie8` & `mangle` (#3524)

fixes #3523

1 files changed, 7 insertions, 1 deletions

diff --git a/lib/scope.js b/lib/scope.js
index 6e33365c..edefc29b 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -214,7 +214,13 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
     function redefine(node, scope) {
         var name = node.name;
         var old_def = node.thedef;
-        var new_def = scope.find_variable(name) || self.globals.get(name) || scope.def_variable(node);
+        var new_def = scope.find_variable(name);
+        if (new_def) {
+            var redef;
+            while (redef = new_def.redefined()) new_def = redef;
+        } else {
+            new_def = self.globals.get(name) || scope.def_variable(node);
+        }
         old_def.orig.concat(old_def.references).forEach(function(node) {
             node.thedef = new_def;
             node.reference(options);