Stops using SYSTEM_STATE_INDETERMINATE as it makes radio buttons appear to have a mixed state.

third_party/WebKit/public/web/WebAXEnums.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 187 matching lines @@
 // Accessibility states, used as a bitmask.
 enum WebAXState {
     WebAXStateBusy,
     WebAXStateChecked,
     WebAXStateEnabled,
     WebAXStateExpanded,
     WebAXStateFocusable,
     WebAXStateFocused,
     WebAXStateHaspopup,
     WebAXStateHovered,
-    WebAXStateIndeterminate,
     WebAXStateInvisible,
     WebAXStateLinked,
     WebAXStateMultiline,
     WebAXStateMultiselectable,
     WebAXStateOffscreen,
     WebAXStatePressed,
     WebAXStateProtected,
     WebAXStateReadonly,
     WebAXStateRequired,
     WebAXStateSelectable,
@@ skipping 77 matching lines @@
     WebAXDescriptionFromUninitialized = -1,
     WebAXDescriptionFromAttribute = 0,
     WebAXDescriptionFromContents,
     WebAXDescriptionFromPlaceholder,
     WebAXDescriptionFromRelatedElement,
 };
 
 } // namespace blink
 
 #endif