Add --modules=node support

lib/runtime/dart/_js_mirrors.js

 dart_library.library('dart/_js_mirrors', null, /* Imports */[
   'dart/_runtime',
   'dart/_internal',
   'dart/core',
   'dart/mirrors'
 ], /* Lazy imports */[
 ], function(exports, dart, _internal, core, mirrors) {
   'use strict';
   let dartx = dart.dartx;
   function getName(symbol) {
@@ skipping 11 matching lines @@
   });
   function reflect(reflectee) {
     return new JsInstanceMirror._(reflectee);
   }
   dart.fn(reflect, mirrors.InstanceMirror, [dart.dynamic]);
   function reflectType(key) {
     return new JsClassMirror._(key);
   }
   dart.fn(reflectType, mirrors.TypeMirror, [core.Type]);
   const _dart = dart;
-  const _metadata = _dart.metadata;
   function _dload(obj, name) {
     return _dart.dload(obj, name);
   }
   dart.fn(_dload, dart.dynamic, [dart.dynamic, core.String]);
   function _dput(obj, name, val) {
     _dart.dput(obj, name, val);
   }
   dart.fn(_dput, dart.void, [dart.dynamic, core.String, dart.dynamic]);
   function _dsend(obj, name, args) {
     return _dart.dsend(obj, name, ...args);
@@ skipping 46 matching lines @@
   dart.setSignature(JsInstanceMirror, {
     constructors: () => ({_: [JsInstanceMirror, [core.Object]]}),
     methods: () => ({
       delegate: [dart.dynamic, [core.Invocation]],
       getField: [mirrors.InstanceMirror, [core.Symbol]],
       setField: [mirrors.InstanceMirror, [core.Symbol, core.Object]],
       invoke: [mirrors.InstanceMirror, [core.Symbol, core.List], [core.Map$(core.Symbol, dart.dynamic)]],
       [_toJsMap]: [dart.dynamic, [core.Map$(core.Symbol, dart.dynamic)]]
     })
   });
-  const _metadata$ = Symbol('_metadata');
+  const _metadata = Symbol('_metadata');
   const _declarations = Symbol('_declarations');
   const _cls = Symbol('_cls');
   class JsClassMirror extends core.Object {
     get metadata() {
-      return this[_metadata$];
+      return this[_metadata];
     }
     get declarations() {
       return this[_declarations];
     }
     _(cls) {
       this[_cls] = cls;
       this.simpleName = core.Symbol.new(cls.name);
-      this[_metadata$] = null;
+      this[_metadata] = null;
       this[_declarations] = null;
       let fn = this[_cls][dart.metadata];
-      this[_metadata$] = fn == null ? dart.list([], mirrors.InstanceMirror) : core.List$(mirrors.InstanceMirror).from(dart.as(dart.dsend(dart.dcall(fn), 'map', dart.fn(i => new JsInstanceMirror._(i), JsInstanceMirror, [dart.dynamic])), core.Iterable));
+      this[_metadata] = fn == null ? dart.list([], mirrors.InstanceMirror) : core.List$(mirrors.InstanceMirror).from(dart.as(dart.dsend(dart.dcall(fn), 'map', dart.fn(i => new JsInstanceMirror._(i), JsInstanceMirror, [dart.dynamic])), core.Iterable));
       this[_declarations] = core.Map$(core.Symbol, mirrors.MethodMirror).new();
       this[_declarations].set(this.simpleName, new JsMethodMirror._(this, this[_cls]));
     }
     newInstance(constructorName, args, namedArgs) {
       if (namedArgs === void 0) namedArgs = null;
       dart.assert(getName(constructorName) == "");
       dart.assert(namedArgs == null || dart.notNull(namedArgs.isEmpty));
       let instance = new this[_cls](...args);
       return new JsInstanceMirror._(instance);
     }
@@ skipping 313 matching lines @@
   exports.getName = getName;
   exports.getSymbol = getSymbol;
   exports.reflect = reflect;
   exports.reflectType = reflectType;
   exports.JsInstanceMirror = JsInstanceMirror;
   exports.JsClassMirror = JsClassMirror;
   exports.JsTypeMirror = JsTypeMirror;
   exports.JsParameterMirror = JsParameterMirror;
   exports.JsMethodMirror = JsMethodMirror;
 });