Valgrind Mac: Suppress a bunch of leaks in test_shell.

tools/valgrind/memcheck/suppressions.txt

 # There are four kinds of suppressions in this file.
 # 1. third party stuff we have no control over
 #
 # 2. intentional unit test errors, or stuff that is somehow a false positive
 # in our own code, or stuff that is so trivial it's not worth fixing
 #
 # 3. Suppressions for real chromium bugs that are not yet fixed.
 # These should all be in chromium's bug tracking system (but a few aren't yet).
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 666 matching lines @@
    fun:pa_set_env_and_record
    fun:main
 }
 
 # The following stack suppresses Memcheck false positives on NaCl browser_tests
 # See https://bugs.kde.org/show_bug.cgi?id=270709#c4 for possible reason
 {
    valgrind_bitfields_false_positive
    Memcheck:Cond
    fun:_ZN7WebCore13WidthIterator*
+   ...
    fun:_ZNK7WebCore4Font33getGlyphsAndAdvancesForSimpleTextERKNS_7TextRunEiiRNS_11GlyphBufferENS0_20ForTextEmphasisOrNotE
    fun:_ZNK7WebCore4Font14drawSimpleTextEPNS_15GraphicsContextERKNS_7TextRunERKNS_10FloatPointEii
    ...
    fun:_ZN7WebCoreL20paintTextWithShadowsEPNS_15GraphicsContextERKNS_4FontERKNS_7TextRunERKN3WTF12AtomicStringEiiiiRKNS_10FloatPointERKNS_9FloatRectEPKNS_10ShadowDataEbb
    fun:_ZN7WebCore13InlineTextBox5paintERNS_9PaintInfoERKNS_8IntPointEii
    ...
    fun:_ZN7WebCore13RootInlineBox5paintERNS_9PaintInfoERKNS_8IntPointEii
    fun:_ZNK7WebCore17RenderLineBoxList5paintEPNS_20RenderBoxModelObjectERNS_9PaintInfoERKNS_8IntPointE
    fun:_ZN7WebCore11RenderBlock*paint*
 }
@@ skipping 4609 matching lines @@
    obj:/lib/libselinux.so.1
    obj:/lib/libselinux.so.1
 }
 {
    bug_todo_grep
    Memcheck:Leak
    fun:malloc
    obj:/bin/grep
    obj:/bin/grep
 }