> run-webkit-tests --world-leaks fast/canvas/webgl/webgl2/bindings.html
> run-webkit-tests --world-leaks fast/canvas/webgl/webgl-reload-crash.html

These canvas tests will report a leaked document but it is not reproducible from MiniBrowser. If you navigate to the test then go to about:blank and issue a low memory warning followed by showAllDocuments, only the about:blank document and page are live.


I tried disabling the BackForwardCache and setting the CacheModel to DocumentBrowser in MiniBrowser to match WKTR but still cannot reproduce the leak. It appears the false positive is indeed due to a leaked document but I think there's something else going on. If you pause the test runner after it gets the list of live documents but before it finishes the test (TestController::didReceiveLiveDocumentsList) then ask for a GC heap dump the leaked document will be collected. Put a breakpoint in Document::~Document and issue the following command:

> notifyutil -p com.apple.WebKit.dumpGCHeap

While the WKTR process is paused the WebContent process will start a GC in response to the notification which will lead to the last JSEventTarget wrapper to be GC'd which will allow the Document to be destroyed. Something specific to WKTR must be keeping documents alive in some layout tests.