Avoid use of empty string as a property name.

sdk/lib/_internal/lib/js_mirrors.dart

Index: sdk/lib/_internal/lib/js_mirrors.dart
diff --git a/sdk/lib/_internal/lib/js_mirrors.dart b/sdk/lib/_internal/lib/js_mirrors.dart
index 0154824bf1bde1521303f615bb696e99416cc782..f16010c893e086599389ddec6ef3c9f108a923f3 100644
--- a/sdk/lib/_internal/lib/js_mirrors.dart
+++ b/sdk/lib/_internal/lib/js_mirrors.dart
@@ -569,7 +569,8 @@ TypeMirror reflectClassByName(Symbol symbol, String mangledName) {
     // This is a native class, or an intercepted class.
     // TODO(ahe): Preserve descriptor for such classes.
   } else {
-    fields = JS('', '#[""]', descriptor);
+    fields = JS('', '#[#]', descriptor,
+        JS_GET_NAME('CLASS_DESCRIPTOR_PROPERTY'));
     if (fields is List) {
       fieldsMetadata = fields.getRange(1, fields.length).toList();
       fields = fields[0];
@@ -1592,7 +1593,10 @@ class JsClassMirror extends JsTypeMirror with JsObjectMirror
     var staticDescriptor = JS('', 'init.statics[#]', _mangledName);
     if (staticDescriptor != null) {
       parseCompactFieldSpecification(
-          fieldOwner, JS('', '#[""]', staticDescriptor), true, result);
+          fieldOwner,
+          JS('', '#[#]',
+              staticDescriptor, JS_GET_NAME('CLASS_DESCRIPTOR_PROPERTY')),
+          true, result);
     }
     return result;
   }