Suppress WebCore::ThreadState::visitStack uninits when it walks the stack

TBR=thestig@chromium.org
BUG=340752

Review URL: https://codereview.chromium.org/164193004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251140 0039d316-1c4b-4281-b951-d872f2087c98

tools/valgrind/memcheck/suppressions.txt

@@ -6346,3 +6346,16 @@
    fun:_ZN5blink11WebViewImpl12setMainFrameEPNS_8WebFrameE
    fun:_ZN7content22BufferedDataSourceTestC2Ev
 }
+{
+   bug_340752
+   Memcheck:Uninitialized
+   ...
+   fun:_ZN7WebCore17HeapContainsCache*
+   fun:_ZN7WebCore11ThreadState19heapPageFromAddressEPh
+   fun:_ZN7WebCore11ThreadState19checkAndMarkPointerEPNS_7VisitorEPh
+   fun:_ZN7WebCore4Heap19checkAndMarkPointerEPNS_7VisitorEPh
+   fun:_ZN7WebCore11ThreadState10visitStackEPNS_7VisitorE
+   fun:_ZN7WebCore11ThreadState5traceEPNS_7VisitorE
+   fun:_ZN7WebCore11ThreadState10visitRootsEPNS_7VisitorE
+   fun:_ZN7WebCore4Heap14collectGarbageENS_11ThreadState10StackStateENS0_6GCTypeE
+}