Revert enumerability change due to performance impact

Setting inherited "private" properties to non-enumerable has a non-
negligible performance impact. While possible for a user to extract
all enumerable keys from an ndarray, this should not be common. For
the stdlib REPL, we should handle ndarrays as a special case when
displaying as a return value. This applies similarly to other JS
objects, such as typed arrays.

Author: kgryte

lib/node_modules/@stdlib/ndarray/ctor/lib/main.js

@@ -21,7 +21,6 @@
 // MODULES //
 
 var setReadOnly = require( '@stdlib/utils/define-nonenumerable-read-only-property' );
-var setNonEnumerable = require( '@stdlib/utils/define-nonenumerable-property' );
 var isArrayLikeObject = require( '@stdlib/assert/is-array-like-object' );
 var isTypedArrayLike = require( '@stdlib/assert/is-typed-array-like' );
 var isBuffer = require( '@stdlib/assert/is-buffer' );
@@ -35,7 +34,6 @@ var isBufferLengthCompatible = require( '@stdlib/ndarray/base/assert/is-buffer-l
 var bytesPerElement = require( '@stdlib/ndarray/base/bytes-per-element' );
 var baseCtor = require( '@stdlib/ndarray/base/memoized-ctor' );
 var inherit = require( '@stdlib/utils/inherit' );
-var objectKeys = require( '@stdlib/utils/keys' );
 var defaults = require( './defaults.json' );
 var igetValue = require( './iget.js' );
 var isetValue = require( './iset.js' );
@@ -139,11 +137,8 @@ function ctor( dtype, ndims, options ) {
 	*/
 	function ndarray( buffer, shape, strides, offset, order ) {
 		/* eslint-disable no-invalid-this */
-		var keys;
 		var sh;
 		var st;
-		var k;
-		var i;
 		if ( !(this instanceof ndarray) ) {
 			return new ndarray( buffer, shape, strides, offset, order );
 		}
@@ -185,14 +180,6 @@ function ctor( dtype, ndims, options ) {
 		// Cache references to the parent constructor and parent constructor methods:
 		setReadOnly( this, '_parent', parent );
 
-		// Make all inherited "private" properties non-enumerable...
-		keys = objectKeys( this );
-		for ( i = 0; i < keys.length; i++ ) {
-			k = keys[ i ];
-			if ( k[ 0 ] === '_' ) {
-				setNonEnumerable( this, k, this[ k ] );
-			}
-		}
 		return this;
 
 		/* eslint-enable no-invalid-this */