clean up webkit quirks (#3229)

lib/scope.js

@@ -320,14 +320,6 @@ function next_mangled_name(scope, options, def) {
     var in_use = names_in_use(scope, options);
     var holes = scope.cname_holes;
     var names = Object.create(null);
-    // #179, #326
-    // in Safari strict mode, something like (function x(x){...}) is a syntax error;
-    // a function expression's argument cannot shadow the function expression's name
-    if (scope instanceof AST_Function && scope.name && def.orig[0] instanceof AST_SymbolFunarg) {
-        var tricky_def = scope.name.definition();
-        // the function's mangled_name is null when keep_fnames is true
-        names[tricky_def.mangled_name || tricky_def.name] = true;
-    }
     var scopes = [ scope ];
     def.references.forEach(function(sym) {
         var scope = sym.scope;