Add spec links for WebGL IDL files

third_party/WebKit/Source/modules/webgl/EXTDisjointTimerQueryWebGL2.idl

 // Copyright 2016 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_disjoint_timer_query_webgl2/
+
 typedef unsigned long long GLuint64EXT;
 
 [
     DependentLifetime,
     DoNotCheckConstants,
     NoInterfaceObject,
 ] interface EXTDisjointTimerQueryWebGL2 {
     const GLenum QUERY_COUNTER_BITS_EXT      = 0x8864;
     const GLenum TIME_ELAPSED_EXT            = 0x88BF;
     const GLenum TIMESTAMP_EXT               = 0x8E28;
     const GLenum GPU_DISJOINT_EXT            = 0x8FBB;
     void queryCounterEXT(WebGLQuery query, GLenum target);
 };