Exclude a UI test failing on an arena assertion on Mac OS, exclude DnsTransactionTest.FirstTimeou...

Exclude a UI test failing on an arena assertion on Mac OS, exclude DnsTransactionTest.FirstTimeoutTest from all TSan runs (was: win-only)

crbug is down now, so writing failure output here instead of adding crbug comments:
http://build.chromium.org/p/chromium.memory/builders/Chromium%20Mac%20UI%20%28valgrind%29%281%29/builds/4693/steps/memory%20test%3A%20ui/logs/stdio
[ RUN      ] UILayoutTest.MediaUILayoutTest
findSb: can't find pointer 0x1F7FE190 in arena 'client'

valgrind: the 'impossible' happened:
   findSb: VG_(arena_free)() in wrong arena?
==44438==    at 0x38034E05: ???

sched status:
  running_tid=1

Thread 1: status = VgTs_Runnable
==44438==    at 0x163FD: free (vg_replace_malloc.c:366)
==44438==    by 0x7E4A1F: inflateEnd (in /usr/lib/libz.1.2.3.dylib)
==44438==    by 0x182B8F35: png_read_destroy (in /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/Resources/libPng.dylib)
==44438==    by 0x182B8C2A: _cg_png_destroy_read_struct (in /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/Resources/libPng.dylib)
==44438==    by 0x397E9B5: _CGImagePluginInitPNG (in /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/ImageIO)
==44438==    by 0x397D37D: makeImagePlus (in /System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/ImageIO.framework/Versions/A/ImageIO)
...
==44438==    by 0xE049E9: -[NSWindow makeKeyAndOrderFront:] (in /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit)
==44438==    by 0xBAD2F84: _ZN18BrowserWindowCocoa4ShowEv (in /b/build/slave/chromium-rel-mac-valgrind-ui-1/build/src/xcodebuild/Release/Chromium.app/Contents/Versions/15.0.856.0/Chromium Framework.framewo


http://build.chromium.org/p/chromium.memory/builders/Chromium%20Mac%20%28tsan%29/builds/8091/steps/memory%20test%3A%20net/logs/stdio
[ RUN      ] DnsTransactionTest.FirstTimeoutTest
[72206:2823:0817/063330:4543072922370295:FATAL:dns_test_util.cc(18)] Check failed: !numbers_.empty().
Backtrace:
  0   net_unittests                       0x00061f03 operator new(unsigned long, void*) + 392087
  1   net_unittests                       0x00061f37 operator new(unsigned long, void*) + 392139
  2   net_unittests                       0x0006231e operator new(unsigned long, void*) + 393138
  3   net_unittests                       0x000625d9 operator new(unsigned long, void*) + 393837
  4   net_unittests                       0x00747ba9 start + 7062665

TBR=glider
BUG=58146, 88225
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=97131