Suppress the Valgrind memory leak from the 58138 webkit roll....

tools/valgrind/memcheck/suppressions.txt

 # There are three 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 # running overnight and removing outdated bugs/suppressions.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 2609 matching lines @@
 }
 {
    bug_42389
    Memcheck:Leak
    fun:malloc
    fun:g_malloc
    ...
    fun:gdk_pixbuf_loader_write
    fun:_ZN10IconLoader9ParseIconEv
 }
+{
+   bug_42590
+   Memcheck:Leak
+   fun:malloc
+   fun:_ZN3WTF10fastMalloc*
+   fun:_ZN7WebCore10StringImpl19createUninitializedEjRPt
+   fun:_ZN7WebCore10StringImpl6createEPKcj
+   fun:_ZN7WebCore10StringImpl6createEPKc
+   fun:_ZN3WTF17CStringTranslator9translateERPN7WebCore10StringImplERKPKcj
+   fun:_ZN3WTF24HashSetTranslatorAdapterIPN7WebCore10StringImplENS_10HashTraitsIS3_EEPKcNS_17CStringTranslatorEE9translateERS3_RKS7_SC_j
+   ...
+   fun:_ZN7WebCore9TimerBase10heapInsertEv
+}