fix various for-of bugs (#2800)

- disable `rename` pass on harmony due to problem with for-of loops

fixes #2794

lib/minify.js

@@ -151,7 +151,9 @@ function minify(files, options) {
             toplevel = toplevel.wrap_commonjs(options.wrap);
         }
         if (timings) timings.rename = Date.now();
-        if (options.rename) {
+        // disable rename on harmony due to expand_names bug in for-of loops
+        // https://github.com/mishoo/UglifyJS2/issues/2794
+        if (0 && options.rename) {
             toplevel.figure_out_scope(options.mangle);
             toplevel.expand_names(options.mangle);
         }