Allow seeks to zero on streaming sources.

Source/core/html/TimeRanges.cpp

 /*
  * Copyright (C) 2007, 2009, 2010 Apple 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 166 matching lines @@
 {
     for (unsigned n = 0; n < length(); n++) {
         if (time >= start(n, IGNORE_EXCEPTION) && time <= end(n, IGNORE_EXCEPTION))
             return true;
     }
     return false;
 }
 
 double TimeRanges::nearest(double time) const
 {
-    double closest = 0;
     unsigned count = length();
+    double bestMatch = 0;
+    double bestDelta = std::numeric_limits<double>::infinity();
     for (unsigned ndx = 0; ndx < count; ndx++) {
         double startTime = start(ndx, IGNORE_EXCEPTION);
         double endTime = end(ndx, IGNORE_EXCEPTION);
         if (time >= startTime && time <= endTime)
             return time;
-        if (fabs(startTime - time) < closest)
-            closest = fabs(startTime - time);
-        else if (fabs(endTime - time) < closest)
-            closest = fabs(endTime - time);
+        if (time < startTime) {
+            double delta = startTime - time;
+            if (delta < bestDelta) {
+                bestMatch = startTime;
+                bestDelta = delta;
+            }
+        } else if (time > endTime) {
+            double delta = time - endTime;
+            if (delta < bestDelta) {
+                bestMatch = endTime;
+                bestDelta = delta;
+            }
+        }
     }
-    return closest;
+    return bestMatch;
 }
 
 void TimeRanges::trace(Visitor* visitor)
 {
     visitor->trace(m_ranges);
 }