Tighten the asserts in VTTCue::calculateDisplayParameters()

Source/core/html/track/vtt/VTTCue.cpp

 /*
  * Copyright (c) 2013, Opera Software ASA. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 608 matching lines @@
                 m_displayPosition.first = m_textPosition - m_displaySize;
             else
                 m_displayPosition.first = 100 - m_textPosition - m_displaySize;
             break;
         case Middle:
             if (m_displayDirection == CSSValueLtr)
                 m_displayPosition.first = m_textPosition - m_displaySize / 2;
             else
                 m_displayPosition.first = 100 - m_textPosition - m_displaySize / 2;
             break;
-        case NumberOfAlignments:
+        default:
             ASSERT_NOT_REACHED();
         }
     } else {
         // Cases for m_writingDirection being VerticalGrowing{Left|Right}
         switch (m_cueAlignment) {
         case Start:
         case Left:
             m_displayPosition.second = m_textPosition;
             break;
         case End:
         case Right:
             m_displayPosition.second = m_textPosition - m_displaySize;
             break;
         case Middle:
             m_displayPosition.second = m_textPosition - m_displaySize / 2;
             break;
-        case NumberOfAlignments:
+        default:
             ASSERT_NOT_REACHED();
         }
     }
 
     // A text track cue has a text track cue computed line position whose value
     // is defined in terms of the other aspects of the cue.
     m_computedLinePosition = calculateComputedLinePosition();
 
     // 10.9 Determine the value of whichever of x-position or y-position is not
     // yet calculated for cue as per the appropriate rules from the following
@@ skipping 439 matching lines @@
 
 void VTTCue::trace(Visitor* visitor)
 {
     visitor->trace(m_vttNodeTree);
     visitor->trace(m_cueBackgroundBox);
     visitor->trace(m_displayTree);
     TextTrackCue::trace(visitor);
 }
 
 } // namespace WebCore