Add String.prototype.search test

test/built-ins/String/prototype/search/cstm-search-is-null.js

@@ -0,0 +1,33 @@
+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-string.prototype.search
+description: >
+  If regexp's Symbol.search property is null, no error is thrown.
+info: |
+  String.prototype.search ( regexp )
+
+  [...]
+  2. If regexp is neither undefined nor null, then
+    a. Let searcher be ? GetMethod(regexp, @@search).
+    b. If searcher is not undefined, then
+      [...]
+  [...]
+  5. Return ? Invoke(rx, @@search, « string »).
+
+  GetMethod ( V, P )
+
+  [...]
+  2. Let func be ? GetV(V, P).
+  3. If func is either undefined or null, return undefined.
+features: [Symbol.search]
+---*/
+
+var regexp = {};
+regexp[Symbol.search] = null;
+regexp.toString = function() { return "\\d"; };
+regexp.valueOf = function() { throw new Test262Error("should not be called"); };
+
+assert.sameValue("abc".search(regexp), -1);
+assert.sameValue("ab3c".search(regexp), 2);