Add --modules=node support

lib/runtime/dart/_js_mirrors.js

Index: lib/runtime/dart/_js_mirrors.js
diff --git a/lib/runtime/dart/_js_mirrors.js b/lib/runtime/dart/_js_mirrors.js
index cc0d71f2d718dba381ddb1212dde1dc2b1f9b2fd..092a56acf2f9e2c7d04d78949ce030a2daba26b4 100644
--- a/lib/runtime/dart/_js_mirrors.js
+++ b/lib/runtime/dart/_js_mirrors.js
@@ -29,7 +29,6 @@ dart_library.library('dart/_js_mirrors', null, /* Imports */[
   }
   dart.fn(reflectType, mirrors.TypeMirror, [core.Type]);
   const _dart = dart;
-  const _metadata = _dart.metadata;
   function _dload(obj, name) {
     return _dart.dload(obj, name);
   }
@@ -96,12 +95,12 @@ dart_library.library('dart/_js_mirrors', null, /* Imports */[
       [_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$];
+      return this[_metadata];
     }
     get declarations() {
       return this[_declarations];
@@ -109,10 +108,10 @@ dart_library.library('dart/_js_mirrors', null, /* Imports */[
     _(cls) {
       this[_cls] = cls;
       this.simpleName = core.Symbol.new(cls.name);
-      this[_metadata$] = 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]));
     }