Remove the suppression for a NULL deref in WebKit support code

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 # running overnight and removing outdated bugs/suppressions.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 5728 matching lines @@
    fun:_ZN3net16HostResolverImpl3Job18OnProcTaskCompleteEiRKNS_11AddressListE
 }
 {
    bug_118336
    Memcheck:Leak
    fun:_Znw*
    ...
    fun:_ZN47SelectFileDialogExtensionTest_SelfDeleting_Test8TestBodyEv
 }
 {
-   bug_118387a
-   Memcheck:Unaddressable
-   fun:_ZN3WTF11currentTimeEv
-   fun:_ZN7WebCore5EventC2ERKN3WTF12AtomicStringEbb
-   fun:_ZN7WebCore19PageTransitionEventC1ERKN3WTF12AtomicStringEb
-   fun:_ZN7WebCore19PageTransitionEvent6createERKN3WTF12AtomicStringEb
-   fun:_ZN7WebCore11FrameLoader11stopLoadingENS_17UnloadEventPolicyE
-   fun:_ZN7WebCore11FrameLoader8closeURLEv
-   fun:_ZN7WebCore11FrameLoader16detachFromParentEv
-   fun:_ZN7WebCore11FrameLoader13frameDetachedEv
-   fun:_ZN7WebCore8SVGImageD0Ev
-}
-{
-   bug_118387b
-   Memcheck:Unaddressable
-   fun:_ZN7WebCore15PlatformSupport20histogramEnumerationEPKcii
-   fun:_ZN7WebCore16HistogramSupport20histogramEnumerationEPKcii
-   fun:_ZN7WebCoreL27histogramMutationEventUsageERKt
-   fun:_ZN7WebCore8DocumentD2Ev
-   fun:_ZN7WebCore11SVGDocumentD0Ev
-}
-{
    bug_118890_a
    Memcheck:Leak
    ...
    fun:_ZN27TestURLRequestContextGetter20GetURLRequestContextEv
    fun:_ZN8notifier18SingleLoginAttemptC1EPNS_13LoginSettingsEPNS0_8DelegateE
    fun:_ZN8notifier5Login15StartConnectionEv
    fun:_ZN13sync_notifier20InvalidationNotifier17UpdateCredentialsERKSsS2_
 }
 {
    bug_118890_b
@@ skipping 49 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
 }