test: simplify regression test for SEGV

Test was introduced in 08a5b44 as a regression test, and has evolved
since then. Simplify the test so that it doesn't rely on an undocumented
argument to tls.createSecureCredentials().

See: nodejs/node-v0.x-archive#6690

Confirmation that this reworked test triggers the original bug:

	%) % node
	> process.version
	'v0.10.48'
	> credentials = crypto.createCredentials()
	{ context: {} }
	> context = credentials.context
	{}
	> notcontext = { setOptions: context.setOptions }
	{ setOptions: [Function: setOptions] }
	> notcontext.setOptions()
	node: ../src/node_object_wrap.h:61: static T* node::ObjectWrap::Unwrap(v8::Handle<v8::Object>) [with T = node::crypto::SecureContext]: Assertion `handle->InternalFieldCount() > 0' failed.
	zsh: abort (core dumped)  node

PR-URL: #24241
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-crypto.js

@@ -38,19 +38,19 @@ const tls = require('tls');
 const fixtures = require('../common/fixtures');
 
 // Test Certificates
-const caPem = fixtures.readSync('test_ca.pem', 'ascii');
-const certPem = fixtures.readSync('test_cert.pem', 'ascii');
 const certPfx = fixtures.readSync('test_cert.pfx');
-const keyPem = fixtures.readSync('test_key.pem', 'ascii');
 
 // 'this' safety
 // https://github.com/joyent/node/issues/6690
 assert.throws(function() {
-  const options = { key: keyPem, cert: certPem, ca: caPem };
-  const credentials = tls.createSecureContext(options);
+  const credentials = tls.createSecureContext();
   const context = credentials.context;
-  const notcontext = { setOptions: context.setOptions, setKey: context.setKey };
-  tls.createSecureContext({ secureOptions: 1 }, notcontext);
+  const notcontext = { setOptions: context.setOptions };
+
+  // Methods of native objects should not segfault when reassigned to a new
+  // object and called illegally. This core dumped in 0.10 and was fixed in
+  // 0.11.
+  notcontext.setOptions();
 }, (err) => {
   // Throws TypeError, so there is no opensslErrorStack property.
   if ((err instanceof Error) &&