GL_ANGLE_texture_compression_dxt5
https://code.google.com/p/angleproject/source/browse/#git%2Fextensions
GL_ANGLE_texture_compression_dxt5
	GL_COMPRESSED_RGB_S3TC_DXT1_ANGLE 0x83F0
	GL_COMPRESSED_RGBA_S3TC_DXT1_ANGLE 0x83F1
	GL_COMPRESSED_RGBA_S3TC_DXT3_ANGLE 0x83F2
	GL_COMPRESSED_RGBA_S3TC_DXT5_ANGLE 0x83F3