Remove an unused Memcheck suppression

BUG=419373
TBR=glider@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/822913002

Cr-Commit-Position: refs/heads/master@{#309553}

tools/valgrind/memcheck/suppressions.txt

@@ -3362,14 +3362,6 @@
    ...
    fun:_ZN16sync_file_system13drive_backend14SyncEngineTest5SetUpEv
 }
-{
-   bug_419373
-   Memcheck:Uninitialized
-   fun:_ZNK5blink20InlineFlowBoxPainter49roundedFrameRectClampedToLineTopAndBottomIfNeededEv
-   fun:_ZN5blink20InlineFlowBoxPainter28paintBoxDecorationBackgroundERNS_9PaintInfoERKNS_11LayoutPointE
-   fun:_ZN5blink20InlineFlowBoxPainter5paintERNS_9PaintInfoERKNS_11LayoutPointENS_10LayoutUnitES6_
-   fun:_ZN5blink13InlineFlowBox5paintERNS_9PaintInfoERKNS_11LayoutPointENS_10LayoutUnitES6_
-}
 {
    bug_422485
    Memcheck:Overlap