The WEBGL_draw_buffers extension is part of the WebGL API and enables a fragment shader to write to several textures, which is useful for deferred shading, for example.
The WebGLVertexArrayObjectOES interface is part of the WebGLOES_vertex_array_object extension, represents vertex array objects (VAOs) pointing to vertex array data and provides names for different sets of vertex data.
The EXT_disjoint_timer_query.createQueryEXT() method of the WebGL API creates and initializes WebGLTimerQueryEXT objects, which track the time needed to fully complete a set of GL commands.
The OES_vertex_array_object.createVertexArrayOES() method of the WebGL API creates and initializes a WebGLVertexArrayObjectOES object that represents a vertex array object (VAO) pointing to vertex array data and which provides names for different sets of vertex data.