Bug 1529407: Correct MSAA accValue and accRole for role="document". r=MarcoZ

1. When role="document" is (redundantly) used on the body element, still expose the URL via accValue, just like we do for role="application".
2. Expose ROLE_SYSTEM_DOCUMENT for role="document" (rather than the string "document") as per the spec. (Chrome already does this, so I don't expect backwards compat problems with clients.)

Differential Revision: https://phabricator.services.mozilla.com/D20582

--HG--
extra : moz-landing-system : lando

accessible/base/RoleMap.h

@@ -958,7 +958,7 @@ ROLE(NON_NATIVE_DOCUMENT,
      "non-native document",
      ATK_ROLE_DOCUMENT_FRAME,
      NSAccessibilityGroupRole,
-     USE_ROLE_STRING,
+     ROLE_SYSTEM_DOCUMENT,
      ROLE_SYSTEM_DOCUMENT,
      java::SessionAccessibility::CLASSNAME_VIEW,
      eNoNameRule)

accessible/windows/msaa/DocAccessibleWrap.cpp

@@ -77,7 +77,8 @@ DocAccessibleWrap::get_accValue(VARIANT aVarChild, BSTR __RPC_FAR* aValue) {
   // If document is being used to create a widget, don't use the URL hack
   roles::Role role = Role();
   if (role != roles::DOCUMENT && role != roles::APPLICATION &&
-      role != roles::DIALOG && role != roles::ALERT)
+      role != roles::DIALOG && role != roles::ALERT &&
+      role != roles::NON_NATIVE_DOCUMENT)
     return hr;
 
   nsAutoString url;