[lib/web_gl] Workaround to Flutter license script choking on web_gl_dart2js.dart

Flutter license script (which collects various licenses) processes only
the first N number of bytes.

Unfortunately, https://dart-review.googlesource.com/c/sdk/+/424741
increased size of the header in sdk/lib/web_gl/dart2js/web_gl_dart2js.dart
so copyright notice in the middle of the file was cut in half and
no longer recognized by the Flutter license script.

Issue: flutter/flutter#168065
CoreLibraryReviewExempt: comment change
Change-Id: I694066223b7fd4724c4856ce7875d64e870ab723
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/425560
Commit-Queue: Srujan Gaddam <[email protected]>
Reviewed-by: Srujan Gaddam <[email protected]>
Auto-Submit: Alexander Markov <[email protected]>

Author: alexmarkov

sdk/lib/web_gl/dart2js/web_gl_dart2js.dart

@@ -25,6 +25,11 @@ import 'dart:_js_helper'
 import 'dart:_foreign_helper' show JS;
 import 'dart:_interceptors' show JavaScriptObject, JSExtendableArray;
 
+// This comment is an extra padding to work around Flutter license script
+// cutting a copyright notice in the middle of this file because it reads
+// only the first kMaxSize bytes of a file.
+// (https://github.com/flutter/flutter/issues/168065)
+
 // Copyright (c) 2012, 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.

tools/dom/templates/html/dart2js/web_gl_dart2js.darttemplate

@@ -24,4 +24,9 @@ import 'dart:_js_helper' show Creates, JSName, Native, Returns, convertDartClosu
 import 'dart:_foreign_helper' show JS;
 import 'dart:_interceptors' show JavaScriptObject, JSExtendableArray;
 
+// This comment is an extra padding to work around Flutter license script
+// cutting a copyright notice in the middle of this file because it reads
+// only the first kMaxSize bytes of a file.
+// (https://github.com/flutter/flutter/issues/168065)
+
 $!GENERATED_DART_FILES