fix corner case in hoist_props (#3947)

fixes #3945

lib/compress.js

@@ -5074,6 +5074,9 @@ merge(Compressor.prototype, {
                 && right.properties.length > 0
                 && all(right.properties, function(prop) {
                     return prop instanceof AST_ObjectKeyVal;
+                })
+                && all(def.references, function(ref) {
+                    return ref.fixed_value() === right;
                 });
         }
     });