static takeVec2Tex(sizePower) {
        return WglTexturePool.take(
            sizePower + currentShaderCoder().vec2.powerSizeOverhead,
            currentShaderCoder().vec2.pixelType);
    }
Allocates a texture for storing an encoded array of 1<<sizePower float-pairs (possibly encoded into bytes).

@param {!int} sizePower
@returns {!WglTexture}