Add spec links for WebGL IDL files

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

 // Copyright 2015 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/WEBGL_compressed_texture_astc/
+
 [
     DependentLifetime,
     NoInterfaceObject,
     DoNotCheckConstants,
 ] interface WebGLCompressedTextureASTC {
     /* Compressed Texture Formats */
     const unsigned long COMPRESSED_RGBA_ASTC_4x4_KHR           = 0x93B0;
     const unsigned long COMPRESSED_RGBA_ASTC_5x4_KHR           = 0x93B1;
     const unsigned long COMPRESSED_RGBA_ASTC_5x5_KHR           = 0x93B2;
     const unsigned long COMPRESSED_RGBA_ASTC_6x5_KHR           = 0x93B3;
@@ skipping 15 matching lines @@
     const unsigned long COMPRESSED_SRGB8_ALPHA8_ASTC_8x5_KHR   = 0x93D5;
     const unsigned long COMPRESSED_SRGB8_ALPHA8_ASTC_8x6_KHR   = 0x93D6;
     const unsigned long COMPRESSED_SRGB8_ALPHA8_ASTC_8x8_KHR   = 0x93D7;
     const unsigned long COMPRESSED_SRGB8_ALPHA8_ASTC_10x5_KHR  = 0x93D8;
     const unsigned long COMPRESSED_SRGB8_ALPHA8_ASTC_10x6_KHR  = 0x93D9;
     const unsigned long COMPRESSED_SRGB8_ALPHA8_ASTC_10x8_KHR  = 0x93DA;
     const unsigned long COMPRESSED_SRGB8_ALPHA8_ASTC_10x10_KHR = 0x93DB;
     const unsigned long COMPRESSED_SRGB8_ALPHA8_ASTC_12x10_KHR = 0x93DC;
     const unsigned long COMPRESSED_SRGB8_ALPHA8_ASTC_12x12_KHR = 0x93DD;
 };