Remove js.ArrayElement.

tests/compiler/dart2js/js_parser_test.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 import 'mock_compiler.dart';
 import 'package:compiler/src/js/js.dart' as jsAst;
 import 'package:compiler/src/js/js.dart' show js;
@@ skipping 156 matching lines @@
     testError("x++ ++ 42"),
     // Shift operators.
     testExpression("x << 5"),
     testExpression("x << y + 1"),
     testExpression("x <<= y + 1"),
     // Array initializers.
     testExpression("x = ['foo', 'bar', x[4]]"),
     testExpression("[]"),
     testError("[42 42]"),
     testExpression('beebop([1, 2, 3])'),
-    // *We can't parse array literals with holes in them.
-    testError("[1,, 2]"),
-    testError("[1,]"),
-    testError("[,]"),
-    testError("[, 42]"),
+    // Array literals with holes in them.
+    testExpression("[1,, 2]"),
+    testExpression("[1,]", "[1]"),
+    testExpression("[1,,]", "[1,,]"),
+    testExpression("[,]"),
+    testExpression("[,,]"),
+    testExpression("[, 42]"),
     // Ternary operator.
     testExpression("x = a ? b : c"),
     testExpression("y = a == null ? b : a"),
     testExpression("y = a == null ? b + c : a + c"),
     testExpression("foo = a ? b : c ? d : e"),
     testExpression("foo = a ? b ? c : d : e"),
     testExpression("foo = (a = v) ? b = w : c = x ? d = y : e = z"),
     testExpression("foo = (a = v) ? b = w ? c = x : d = y : e = z"),
     // Stacked assignment.
     testExpression("a = b = c"),
     testExpression("var a = b = c"),
   ]));
 }