Remove redundant and confusing test. (#2728)

The syntax error here is already tested by `language/expressions/delete/identifier-strict.js`. The description is just wrong.

test/language/expressions/delete/11.4.1-5-a-5gs.js

@@ -1,18 +0,0 @@
-// Copyright (c) 2012 Ecma International.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-es5id: 11.4.1-5-a-5gs
-description: >
-    Strict Mode - SyntaxError is thrown when deleting a variable which
-    is primitive type(boolean)
-negative:
-  phase: parse
-  type: SyntaxError
-flags: [onlyStrict]
----*/
-
-$DONOTEVALUATE();
-
-var _11_4_1_5 = 7;
-delete _11_4_1_5;