Disable DidAccessInitialDocumentBodyBeforeModalDialog on Win

For some reason a single bot, WebKit XP (deps), is failing on it and
aborting. It's likely a deeper issue than this test. Disabling the test
to see if the other tests would pass.

BUG=312192
TBR=jsbell,dglazkov

Review URL: https://codereview.chromium.org/48333002

git-svn-id: svn://svn.chromium.org/blink/trunk@160712 bbb929c8-8fbe-4397-9dbb-9b2b20218538