Implement WEBGL_compressed_texture_es3_0 extension for WebGL 1/2

gpu/GLES2/extensions/CHROMIUM/CHROMIUM_compressed_texture_es3_0.txt

+Name
+
+    CHROMIUM_compressed_texture_es3_0
+
+Name Strings
+
+    GL_CHROMIUM_compressed_texture_es3_0
+
+Version
+
+    Last Modifed Date: September 19, 2016
+
+Dependencies
+
+    OpenGL ES 2.0 is required.
+
+Overview
+
+    This extension exposes the OpenGL ES 3.0 core compressed texture
+    formats in OpenGL ES 2.0.
+
+New Procedures and Functions
+
+    None
+
+New Tokens
+
+    Accepted by the <internalformat> parameter of CompressedTexImage2D and the
+    <format> parameter of CompressedTexSubImage2D:
+
+        COMPRESSED_R11_EAC                                0x9270
+        COMPRESSED_SIGNED_R11_EAC                         0x9271
+        COMPRESSED_RG11_EAC                               0x9272
+        COMPRESSED_SIGNED_RG11_EAC                        0x9273
+        COMPRESSED_RGB8_ETC2                              0x9274
+        COMPRESSED_SRGB8_ETC2                             0x9275
+        COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2          0x9276
+        COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2         0x9277
+        COMPRESSED_RGBA8_ETC2_EAC                         0x9278
+        COMPRESSED_SRGB8_ALPHA8_ETC2_EAC                  0x9279
+
+    Querying COMPRESSED_TEXTURE_FORMATS will include these new formats.
+
+New Procedures and Functions
+
+    None.
+
+Errors
+
+    The error INVALID_VALUE is generated if the <internalformat> parameter of
+    CompressedTexImage2D or the <format> parameter of CompressedTexSubImage2D is
+    COMPRESSED_R11_EAC, COMPRESSED_SIGNED_R11_EAC, COMPRESSED_RGB8_ETC2,
+    COMPRESSED_SRGB8_ETC2, COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2 or
+    COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2, and imageSize is not
+
+        floor((width + 3) / 4) * floor((height + 3) / 4) * 8
+
+    The error INVALID_VALUE is generated if the <internalformat> parameter of
+    CompressedTexImage2D or the <format> paremeter of CompressedTexSubImage2D is
+    COMPRESSED_RG11_EAC, COMPRESSED_SIGNED_RG11_EAC, COMPRESSED_RGBA8_ETC2_EAC,
+    or COMPRESSED_SRGB8_ALPHA8_ETC2_EAC, and imageSize is not
+
+        floor((width + 3) / 4) * floor((height + 3) / 4) * 16
+
+
+New State
+
+    None.
+
+Revision History
+
+    9/19/2016   First revision