Remove suppression for a race that was fixed a while ago....

tools/valgrind/tsan/suppressions.txt

 ############################
 # Chromium
 
 {
   bug_21259
   ThreadSanitizer:Race
   ...
   fun:*tracked_objects*ThreadData*StartTracking*
 }
 
@@ skipping 81 matching lines @@
 ############################
 # Real races in third_party
 {
   bug_23244 (libevent)
   ThreadSanitizer:Race
   fun:event_*
   fun:event_*
 }
 
 {
-  bug_25645 (WebKit)
-  ThreadSanitizer:Race
-  fun:*WTF*RefCountedBase*ref*
-  ...
-  fun:*WebCore*StringImpl*
-}
-
-{
   bug_25913 (libjingle) (1)
   ThreadSanitizer:Race
   fun:*talk_base*MessageQueue*Stop*
 }
 
 {
   bug_25913 (libjingle) (2)
   ThreadSanitizer:Race
   fun:*talk_base*MessageQueue*Get*
 }
@@ skipping 137 matching lines @@
 
 # fprintf is thread-safe. The benign races happen on the internal lock.
 {
   Benign races below fprintf
   ThreadSanitizer:Race
   ...
   fun:buffered_vfprintf
   ...
   fun:fprintf
 }