Fixing an issue where EXTDrawBuffers.drawBuffersEXT was not getting generated.

sdk/lib/web_gl/dart2js/web_gl_dart2js.dart

Index: sdk/lib/web_gl/dart2js/web_gl_dart2js.dart
diff --git a/sdk/lib/web_gl/dart2js/web_gl_dart2js.dart b/sdk/lib/web_gl/dart2js/web_gl_dart2js.dart
index 0a35ac158e73d3cb6ffbf907f4e59e2a2ce21f9b..fe7e368db90ef43aeddeee7fd315d68c2568b8b9 100644
--- a/sdk/lib/web_gl/dart2js/web_gl_dart2js.dart
+++ b/sdk/lib/web_gl/dart2js/web_gl_dart2js.dart
@@ -691,6 +691,12 @@ class ExtDrawBuffers native "EXTDrawBuffers" {
   @DomName('EXTDrawBuffers.MAX_DRAW_BUFFERS_EXT')
   @DocsEditable
   static const int MAX_DRAW_BUFFERS_EXT = 0x8824;
+
+  @JSName('drawBuffersEXT')
+  @DomName('EXTDrawBuffers.drawBuffersEXT')
+  @DocsEditable
+  @Experimental // untriaged
+  void drawBuffersExt(List<int> buffers) native;
 }
 // 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