Add upsert tests

[dminor]

These tests are currently being executed in SpiderMonkey as non262 tests, and were exported using the test262-export.py script. Linting errors were then corrected.

[ptomato]

Thanks!

This is staging, so you should feel free to (and already have the appropriate permissions to) commit these as long as they are executable by other engines' test262 harnesses.

That said, I suspect they will not pass in any other engines unless you add includes: [sm/non262.js, sm/non262-shell.js] to each one.

Optionally, there's also some low-hanging fruit that could make them slightly more ready to move out of staging when the time comes:

• Add a feature for the upsert proposal to features.txt and add it to features in the frontmatter of each test
• Use verifyProperty instead of assert.deepEqual(Object.getOwnPropertyDescriptor(...etc))
• Use assert.throws(ExceptionType, function () { ... }) instead of assertThrowsInstanceOf(function () { ... }, ExceptionType)

[dminor]

Thanks for the suggestions on how to fix these up, I'll look into that next week prior to committing.