Mangling externally imported names by using aliasing

lib/parse.js

@@ -1667,6 +1667,14 @@ function parse($TEXT, options) {
         }
         name = as_symbol(AST_SymbolImport);
 
+        if (foreign_name === undefined) {
+            foreign_name = new AST_SymbolImportForeign({
+                name: name.name,
+                start: name.start,
+                end: name.end,
+            });
+        }
+
         return new AST_NameImport({
             start: start,
             foreign_name: foreign_name,