Delete the suppression for bug 83566, which seems to be fixed.

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 # running overnight and removing outdated bugs/suppressions.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 3050 matching lines @@
    fun:_ZN6chrome26ChromeContentBrowserClient24RenderProcessHostCreatedEPN7content17RenderProcessHostE
    fun:_ZN21RenderProcessHostImpl4Init*
    ...
    fun:_ZN15WebContentsImpl32CreateRenderViewForRenderManagerEP*
    fun:_ZN21RenderViewHostManager14InitRenderViewEP*
    ...
    fun:_ZN21RenderViewHostManager8NavigateERKN7content19NavigationEntryImplE
    fun:_ZN15WebContentsImpl15NavigateToEntryERKN7content19NavigationEntryImplENS0_20NavigationController10ReloadTypeE
 }
 {
-   bug_83566
-   Memcheck:Unaddressable
-   fun:_ZN7WebCore*V8Entr*Callback11handleEvent*
-   ...
-   fun:_ZN6WebKit31WorkerFileSystemCallbacksBridge21runTaskOnWorkerThreadEPN7WebCore22ScriptExecutionContextEN3WTF10PassRefPtrIS0_EENS4_10PassOwnPtrINS2_4TaskEEE
-   fun:_ZN7WebCore16CrossThreadTask2IN3WTF10PassRefPtrIN6WebKit31WorkerFileSystemCallbacksBridgeEEES5_NS1_10PassOwnPtrINS_22ScriptExecutionContext4TaskEEES9_E11performTaskEPS7_
-   fun:_ZN7WebCore13WorkerRunLoop4Task11performTaskEPNS_22ScriptExecutionContextE
-   fun:_ZN7WebCore13WorkerRunLoop9runInModeEPNS_13WorkerContextERKNS_13ModePredicateE
-   fun:_ZN7WebCore13WorkerRunLoop3runEPNS_13WorkerContextE
-   fun:_ZN7WebCore12WorkerThread12runEventLoopEv
-   fun:_ZN7WebCore21DedicatedWorkerThread12runEventLoopEv
-   fun:_ZN7WebCore12WorkerThread12workerThreadEv
-}
-{
    bug_83609
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN4base4Bind*TaskClosureAdapterEFvvEPS2_EENS_8internal20InvokerStorageHolderINS6_15InvokerStorage1IT_T0_EEEES9_RKSA_
    fun:_ZN11MessageLoop15PostDelayedTaskERKN15tracked_objects8LocationEP4Taskx
    fun:_ZN13BrowserThread14PostTaskHelperENS_2IDERKN15tracked_objects8LocationEP4Taskxb
    fun:_ZN13BrowserThread8PostTaskENS_2IDERKN15tracked_objects8LocationEP4Task
 }
 {
    bug_83609b
@@ skipping 2718 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
 }