Create virtual buffer for Chrome content even if STATE_SYSTEM_BUSY is present

[joanmarie]

As described in this Chromium bug, it was pointed out to me that adding the busy state on documents during load could by side effect cause NVDA to not create a virtual buffer until loading was complete. Therefore, my Chromium change adds the busy state for all platforms but then strips it out for IA2 so as not to introduce any problems for NVDA users.

Since a page in the process of loading is arguably busy, it would be great if NVDA did not block virtual buffer creation on the presence of this state so that we can remove the special handling for IA2.

Thanks in advance for considering this!