Remove suppressions for two bug issues

tools/valgrind/tsan/suppressions.txt

Index: tools/valgrind/tsan/suppressions.txt
===================================================================
--- tools/valgrind/tsan/suppressions.txt	(revision 32025)
+++ tools/valgrind/tsan/suppressions.txt	(working copy)
@@ -2,13 +2,6 @@
 # Chromium
 
 {
-  bug_21259
-  ThreadSanitizer:Race
-  ...
-  fun:*tracked_objects*ThreadData*StartTracking*
-}
-
-{
   bug_21468
   ThreadSanitizer:Race
   ...
@@ -47,22 +40,6 @@
 }
 
 {
-  bug_24715 (1)
-  ThreadSanitizer:Race
-  fun:*base*internal*WeakReference*
-  ...
-  fun:*AppCacheUpdateJobTest*
-}
-
-{
-  bug_24715 (2)
-  ThreadSanitizer:Race
-  fun:*base*internal*WeakReference*
-  ...
-  fun:*AppCacheResponseTest*
-}
-
-{
   bug_25385
   ThreadSanitizer:Race
   ...