Valgrind: Remove an unused suppression for MHTML code.

BUG=122457
TBR=benwells@chromium.org

Review URL: https://codereview.chromium.org/1834223007

Cr-Commit-Position: refs/heads/master@{#383890}

tools/valgrind/memcheck/suppressions.txt

@@ -1345,18 +1345,6 @@
    fun:_tnl_draw_prims
    fun:_tnl_vbo_draw_prims
 }
-{
-   bug_122457
-   Memcheck:Leak
-   fun:malloc
-   fun:_ZN3WTF10fastMallocEm
-   fun:_ZN3WTF10RefCountedIN5blink12MHTMLArchiveEEnwEm
-   fun:_ZN5blink12MHTMLArchive6createEv
-   ...
-   fun:_ZN5blink11MHTMLParser22parseArchiveWithHeaderEPNS_10MIMEHeaderE
-   fun:_ZN5blink11MHTMLParser12parseArchiveEv
-   fun:_ZN5blink12MHTMLArchive6createERKNS_4KURLEPNS_12SharedBufferE
-}
 {
    bug_122717_use_after_free
    Memcheck:Unaddressable