Use a symbol for static length/name (conflicts with Function properties in ES5: cannot redefine Fun…

test/codegen/expect/closure.js

 dart_library.library('closure', null, /* Imports */[
   'dart/_runtime',
   'dart/core',
   'dart/js'
 ], /* Lazy imports */[
 ], function(exports, dart, core, js) {
   'use strict';
   let dartx = dart.dartx;
   /** @typedef {function({i: (?number|undefined)}=)} */
   const Callback = dart.typedef('Callback', () => dart.functionType(dart.void, [], {i: core.int}));
@@ skipping 49 matching lines @@
         if (c === void 0) c = null;
       }
       /**
        * @param {?} a
        * @param {{b: (?|undefined), c: (?|undefined)}=} opts
        */
       static named_params(a, opts) {
         let b = opts && 'b' in opts ? opts.b : null;
         let c = opts && 'c' in opts ? opts.c : null;
       }
+      static [dartx.name]() {
+        return 'Foo.name()';
+      }
+      static [dartx.length]() {
+        return 'Foo.length()';
+      }
+      static [dartx.arguments]() {
+        return 'Foo.arguments()';
+      }
+      static [dartx.caller]() {
+        return 'Foo.caller()';
+      }
+      static [dartx.callee]() {
+        return 'Foo.callee()';
+      }
       nullary_method() {}
       /**
        * @param {function(?, ?=):?number} f
        * @param {function(?, {y: (string|undefined), z: (?|undefined)}=):?} g
        * @param {Callback} cb
        */
       function_params(f, g, cb) {
         dart.as(f, dart.functionType(core.int, [dart.dynamic], [dart.dynamic]));
         dart.as(g, dart.functionType(dart.dynamic, [dart.dynamic], {y: core.String, z: dart.dynamic}));
         cb({i: this.i});
@@ skipping 17 matching lines @@
         build: [Foo$(T), []]
       }),
       methods: () => ({
         untyped_method: [dart.dynamic, [dart.dynamic, dart.dynamic]],
         pass: [T, [T]],
         typed_method: [core.String, [Foo$(), core.List, core.int, core.num, core.double, core.bool, core.String, js.JsArray, js.JsObject, js.JsFunction]],
         optional_params: [dart.dynamic, [dart.dynamic], [dart.dynamic, dart.dynamic]],
         nullary_method: [dart.dynamic, []],
         function_params: [dart.dynamic, [dart.functionType(core.int, [dart.dynamic], [dart.dynamic]), dart.functionType(dart.dynamic, [dart.dynamic], {y: core.String, z: dart.dynamic}), Callback]]
       }),
-      statics: () => ({named_params: [dart.dynamic, [dart.dynamic], {b: dart.dynamic, c: dart.dynamic}]}),
-      names: ['named_params']
+      statics: () => ({
+        named_params: [dart.dynamic, [dart.dynamic], {b: dart.dynamic, c: dart.dynamic}],
+        [dartx.name]: [dart.dynamic, []],
+        [dartx.length]: [dart.dynamic, []],
+        [dartx.arguments]: [dart.dynamic, []],
+        [dartx.caller]: [dart.dynamic, []],
+        [dartx.callee]: [dart.dynamic, []]
+      }),
+      names: ['named_params', dartx.name, dartx.length, dartx.arguments, dartx.caller, dartx.callee]
     });
     /** @final {string} */
     Foo.some_static_constant = "abc";
     /** @final {string} */
     Foo.some_static_final = "abc";
     /** @type {string} */
     Foo.some_static_var = "abc";
     return Foo;
   });
   let Foo = Foo$();
   class Bar extends core.Object {}
   class Baz extends dart.mixin(Foo$(core.int), Bar) {
     /** @param {?number} i */
     Baz(i) {
       super.Foo(i, 123);
     }
   }
   dart.setSignature(Baz, {
     constructors: () => ({Baz: [Baz, [core.int]]})
   });
   /** @param {?} args */
   function main(args) {
+    core.print(Foo[dartx.name]());
+    core.print(Foo[dartx.length]());
+    core.print(Foo[dartx.arguments]());
+    core.print(Foo[dartx.caller]());
+    core.print(Foo[dartx.callee]());
   }
   dart.fn(main, dart.void, [dart.dynamic]);
   /** @final {string} */
   const some_top_level_constant = "abc";
   /** @final {string} */
   exports.some_top_level_final = "abc";
   /** @type {string} */
   exports.some_top_level_var = "abc";
+  dart.defineExtensionNames([
+    "name",
+    "length",
+    "arguments",
+    "caller",
+    "callee"
+  ]);
   // Exports:
   exports.Callback = Callback;
   exports.Foo$ = Foo$;
   exports.Foo = Foo;
   exports.Bar = Bar;
   exports.Baz = Baz;
   exports.main = main;
   exports.some_top_level_constant = some_top_level_constant;
 });