dart2js: Default values for static functions are now inside closures. (in the startup emitter).

sdk/lib/_internal/js_runtime/lib/js_helper.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library _js_helper;
 
 import 'dart:_async_await_error_codes' as async_error_codes;
 
 import 'dart:_js_embedded_names' show
     DEFERRED_LIBRARY_URIS,
@@ skipping 1238 matching lines @@
 
     int argumentCount = arguments.length;
 
     int requiredParameterCount = JS('int', r'#[#]', function,
           JS_GET_NAME(JsGetName.REQUIRED_PARAMETER_PROPERTY));
 
     if (argumentCount < requiredParameterCount) {
       return functionNoSuchMethod(function, arguments, namedArguments);
     }
 
-    var defaultValues = JS('var', r'#[#]', function,
+    var defaultValuesClosure = JS('var', r'#[#]', function,
           JS_GET_NAME(JsGetName.DEFAULT_VALUES_PROPERTY));
-    if (JS('bool', 'typeof # == "function"', defaultValues)) {
-      // Anonymous closures return a function that returns the default values
-      // instead of providing the default values directly.
-      defaultValues = JS('', '#()', defaultValues);
-    }
-    bool acceptsOptionalArguments = defaultValues != null;
+
+    bool acceptsOptionalArguments = defaultValuesClosure != null;
+
+    // Default values are stored inside a JavaScript closure to avoid
+    // accessing them too early.
+    var defaultValues = acceptsOptionalArguments
+        ? JS('', '#()', defaultValuesClosure)
+        : null;
 
     var interceptor = getInterceptor(function);
     var jsFunction = JS('', '#[#]', interceptor,
         JS_GET_NAME(JsGetName.CALL_CATCH_ALL));
     if (jsFunction is String) {
       // Anonymous closures redirect to the catch-all property instead of
       // storing the catch-all method directly in the catch-all property.
       jsFunction = JS('', '#[#]', interceptor, jsFunction);
     }
 
@@ skipping 2982 matching lines @@
   // This is a function that will return a helper function that does the
   // iteration of the sync*.
   //
   // Each invocation should give a body with fresh state.
   final dynamic /* js function */ _outerHelper;
 
   SyncStarIterable(this._outerHelper);
 
   Iterator get iterator => new SyncStarIterator(JS('', '#()', _outerHelper));
 }