mangle destructuring function parameters (#2029)

fixes #2025

lib/scope.js

@@ -51,7 +51,6 @@ function SymbolDef(scope, index, orig) {
     this.global = false;
     this.export = false;
     this.mangled_name = null;
-    this.object_destructuring_arg = false;
     this.undeclared = false;
     this.index = index;
     this.id = SymbolDef.next_id++;
@@ -65,7 +64,6 @@ SymbolDef.prototype = {
 
         return (this.global && !options.toplevel)
             || this.export
-            || this.object_destructuring_arg
             || this.undeclared
             || (!options.eval && (this.scope.uses_eval || this.scope.uses_with))
             || (options.keep_fnames
@@ -168,9 +166,6 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
         if (node instanceof AST_Symbol) {
             node.scope = scope;
         }
-        if (node instanceof AST_SymbolFunarg) {
-            node.object_destructuring_arg = !!in_destructuring;
-        }
         if (node instanceof AST_Label) {
             node.thedef = node;
             node.references = [];
@@ -378,7 +373,6 @@ AST_Scope.DEFMETHOD("def_variable", function(symbol){
     if (!this.variables.has(symbol.name)) {
         def = new SymbolDef(this, this.variables.size(), symbol);
         this.variables.set(symbol.name, def);
-        def.object_destructuring_arg = symbol.object_destructuring_arg;
         def.global = !this.parent_scope;
     } else {
         def = this.variables.get(symbol.name);