test: add test for let bindings in for loops

0724602 floats a patch on V8 that fixes
issue nodejs#9113 that would cause let bindings and continue statements in for
loops to not work properly.

This change adds a regression test that fails if that patch is not
properly floated, thus preventing us from not floating that patch after
future V8 upgrades.

test/simple/test-let-bindings-for-loop-harmony.js

@@ -0,0 +1,38 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+/*
+ * This is a regression test for the issue described at:
+ * https://github.com/joyent/node/issues/9113.
+ *
+ * This problem has been fixed by floating a patch on V8, this test makes
+ * sure that the appropriate patch is floated even after future V8 upgrades.
+ *
+ * If the bug is reproduced, this test stalls and the tests suite makes it
+ * time out eventually (currently after one minute). Otherwise it exits after
+ * the for loop completes its execution.
+ */
+var spawn = require('child_process').spawn;
+var args = ['--harmony',
+            '--use-strict',
+            '-e',
+            'for (let i = 0; i < 3; ++i) { if (i == 1) { continue; } }'];
+var child = spawn(process.execPath, args);