Bug 1421402 - Add an environment variable for controlling the accessible blocklist. r=aklotz

MozReview-Commit-ID: GFCRbrfva7A

--HG--
extra : rebase_source : 88c8e6e5d9b1f87e20712f3f77ade940e9b3570c

accessible/windows/msaa/LazyInstantiator.cpp

@@ -245,6 +245,11 @@ static const wchar_t* gBlockedInprocDlls[] = {
 bool
 LazyInstantiator::IsBlockedInjection()
 {
+  // Check debugging options see if we should disable the blocklist.
+  if (PR_GetEnv("MOZ_DISABLE_ACCESSIBLE_BLOCKLIST")) {
+    return false;
+  }
+
   if (Compatibility::HasKnownNonUiaConsumer()) {
     // If we already see a known AT, don't block a11y instantiation
     return false;