[JSC] IndexedDB: Can't create object store with null keyPath

[Long Xiang]

running below JavaScript code in set version onsuccess callback:
    db.createObjectStore(objectStoreName, {keyPath: null});
will trigger IDB_SYNTAX_ERR exception other than successfully create an object store with out-of-line keys.
Refer to http://www.w3.org/TR/2011/WD-IndexedDB-20111206/#widl-IDBDatabase-createObjectStore-IDBObjectStore-DOMString-name-IDBObjectStoreParameters-optionalParameters 

in WebCore::IDBDatabase::createObjectStore function:
...
Vector<String> keyPathArray;
if (options.get("keyPath", keyPathArray))
    keyPath = IDBKeyPath(keyPathArray);
...
The options.get() will successfully return true with an empty vector other than return false.

in WebCore::JSDictionary::tryGetPropertyAndResult function:

    case PropertyFound: {
        Result result;
        convertValue(m_exec, value, result);
...
convertValue will return normally when the value is undefined or null, and improperly set the empty result to context.
Chromium with V8 binding doesn't have this issue.

[Sihui Liu]

Close this as this is fixed in latest Safari on macOS Monterey 12.3 beta. Tested with following code and no error:

var request = indexedDB.open('test'); 
request.onupgradeneeded = function(event) 
{  
    event.target.result.createObjectStore('os', { keyPath: null }); 
}