Add spec links for WebGL IDL files

third_party/WebKit/Source/modules/webgl/EXTsRGB.idl

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// https://www.khronos.org/registry/webgl/extensions/EXT_sRGB/
+
 [
     DependentLifetime,
     NoInterfaceObject,
     DoNotCheckConstants,
 ] interface EXTsRGB {
     const unsigned long SRGB_EXT                                     = 0x8C40;
     const unsigned long SRGB_ALPHA_EXT                               = 0x8C42;
     const unsigned long SRGB8_ALPHA8_EXT                             = 0x8C43;
     const unsigned long FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING_EXT    = 0x8210;
 };