test: changed test1 of test-vm-timeout.js

test: changed test1 of test-vm-timeout.js so that entire error message
would be matched in assert.throw.

Before test 1 of test-vm-timeout.js would match any error,
now it looks specifically for the error message
"Script execution timed out."

PR-URL: nodejs/node#11590
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-vm-timeout.js

@@ -6,7 +6,7 @@ const vm = require('vm');
 // Test 1: Timeout of 100ms executing endless loop
 assert.throws(function() {
   vm.runInThisContext('while(true) {}', { timeout: 100 });
-});
+}, /^Error: Script execution timed out\.$/);
 
 // Test 2: Timeout must be >= 0ms
 assert.throws(function() {