suppress hoist_props on export (#2463)

Miscellaneous
- fix double semi-colons from `beautify` in `export`

fixes #2462

lib/compress.js

@@ -2895,7 +2895,8 @@ merge(Compressor.prototype, {
         self.variables.each(function(def, name) {
             var_names[name] = true;
         });
-        return self.transform(new TreeTransformer(function(node) {
+        var tt = new TreeTransformer(function(node) {
+            if (node instanceof AST_Definitions && tt.parent() instanceof AST_Export) return node;
             if (node instanceof AST_VarDef) {
                 var sym = node.name, def, value;
                 if (sym.scope === self
@@ -2946,7 +2947,8 @@ merge(Compressor.prototype, {
                 var_names[name] = true;
                 return new_var;
             }
-        }));
+        });
+        return self.transform(tt);
     });
 
     // drop_side_effect_free()