Implement WEBGL_compressed_texture_es3_0 extension for WebGL 1/2

third_party/WebKit/Source/modules/webgl/WebGLCompressedTextureES30.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.
+
+[
+    NoInterfaceObject,
+    DoNotCheckConstants,
+    SetWrapperReferenceFrom=canvas,
+] interface WebGLCompressedTextureES30 {
+    /* Compressed Texture Format */
+    const unsigned long COMPRESSED_R11_EAC                        = 0x9270;
+    const unsigned long COMPRESSED_SIGNED_R11_EAC                 = 0x9271;
+    const unsigned long COMPRESSED_RG11_EAC                       = 0x9272;
+    const unsigned long COMPRESSED_SIGNED_RG11_EAC                = 0x9273;
+    const unsigned long COMPRESSED_RGB8_ETC2                      = 0x9274;
+    const unsigned long COMPRESSED_SRGB8_ETC2                     = 0x9275;
+    const unsigned long COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2  = 0x9276;
+    const unsigned long COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2 = 0x9277;
+    const unsigned long COMPRESSED_RGBA8_ETC2_EAC                 = 0x9278;
+    const unsigned long COMPRESSED_SRGB8_ALPHA8_ETC2_EAC          = 0x9279;
+};