async compileEquirectangularShader() {

		if ( this._equirectMaterial === null ) {

			this._equirectMaterial = _getEquirectMaterial();
			await this._compileMaterial( this._equirectMaterial );

		}

	}
Pre-compiles the equirectangular shader. You can get faster start-up by invoking this method during
your texture's network fetch for increased concurrency.

@returns {Promise}