make `collapse_vars` consistent with `toplevel` (#1608)

fixes #1605

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 49b618e7..dac1f364 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -521,6 +521,7 @@ merge(Compressor.prototype, {
 
             var self = compressor.self();
             var var_defs_removed = false;
+            var toplevel = compressor.option("toplevel");
             for (var stat_index = statements.length; --stat_index >= 0;) {
                 var stat = statements[stat_index];
                 if (stat instanceof AST_Definitions) continue;
@@ -558,7 +559,8 @@ merge(Compressor.prototype, {
 
                     // Only interested in cases with just one reference to the variable.
                     var def = self.find_variable && self.find_variable(var_name);
-                    if (!def || !def.references || def.references.length !== 1 || var_name == "arguments") {
+                    if (!def || !def.references || def.references.length !== 1
+                        || var_name == "arguments" || (!toplevel && def.global)) {
                         side_effects_encountered = true;
                         continue;
                     }