Fix some problems reported by clang static analyzer

Source/core/rendering/RenderMediaControls.cpp

 /*
  * Copyright (C) 2009 Apple Inc.
  * Copyright (C) 2009 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 138 matching lines @@
     int startOffset = startPosition;
     int endOffset = rect.width() - endPosition;
     int rangeWidth = endPosition - startPosition;
 
     if (rangeWidth <= 0)
         return;
 
     // Make sure the range width is bigger than border radius at the edges to retain rounded corners.
     if (startOffset < borderRadius && rangeWidth < borderRadius)
         rangeWidth = borderRadius;
-    if (endOffset < borderRadius && rangeWidth < borderRadius) {
-        startPosition -= borderRadius - rangeWidth;
+    if (endOffset < borderRadius && rangeWidth < borderRadius)
         rangeWidth = borderRadius;
-    }
 
     // Set rectangle to highlight range.
     IntRect highlightRect = rect;
     highlightRect.move(startOffset, 0);
     highlightRect.setWidth(rangeWidth);
 
     // Don't bother drawing an empty area.
     if (highlightRect.isEmpty())
         return;
 
@@ skipping 270 matching lines @@
 {
     return formatChromiumMediaControlsTime(time, time);
 }
 
 String RenderMediaControls::formatMediaControlsCurrentTime(float currentTime, float duration)
 {
     return formatChromiumMediaControlsTime(currentTime, duration);
 }
 
 } // namespace WebCore