Fix harfbuzz read past end of string on arabic text.

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 # running overnight and removing outdated bugs/suppressions.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 975 matching lines @@
    fun:_ZNK14WebPreferences5ApplyEP7WebView
    fun:_ZN10RenderView4InitEiPN4base13WaitableEventEiRK19RendererPreferencesPNS0_14RefCountedDataIiEEi
    fun:_ZN10RenderView6CreateEP16RenderThreadBaseiPN4base13WaitableEventEiRK19RendererPreferencesRK14WebPreferencesPNS2_14RefCountedDataIiEEi
    fun:_ZN12RenderThread15OnCreateNewViewEi16ModalDialogEventRK19RendererPreferencesRK14WebPreferencesi
    ...
    fun:_Z12RendererMainRK18MainFunctionParams
    fun:ChromeMain
    fun:main
 }
 {
-   bug_23450
-   Memcheck:Addr2
-   fun:getArabicProperties
-   fun:arabicSyriacOpenTypeShape
-   fun:HB_ArabicShape
-   fun:HB_ShapeItem
-   fun:_ZN7WebCore13TextRunWalker11shapeGlyphsEv
-   fun:_ZN7WebCore13TextRunWalker13nextScriptRunEv
-   fun:_ZN7WebCore13TextRunWalker14widthOfFullRunEv
-   fun:_ZNK7WebCore4Font24floatWidthForComplexTextERKNS_7TextRunEPN3WTF7HashSetIPKNS_14SimpleFontDataENS4_7PtrHashIS8_EENS4_10HashTraitsIS8_EEEE
-   fun:_ZNK7WebCore4Font10floatWidthERKNS_7TextRunEPN3WTF7HashSetIPKNS_14SimpleFontDataENS4_7PtrHashIS8_EENS4_10HashTraitsIS8_EEEE
-   fun:_ZN7WebCore13RenderListBox17updateFromElementEv
-   fun:_ZN7WebCore22HTMLFormControlElement11recalcStyleENS_4Node11StyleChangeE
-   fun:_ZN7WebCore17HTMLSelectElement11recalcStyleENS_4Node11StyleChangeE
-   fun:_ZN7WebCore7Element11recalcStyleENS_4Node11StyleChangeE
-   fun:_ZN7WebCore7Element11recalcStyleENS_4Node11StyleChangeE
-   fun:_ZN7WebCore8Document11recalcStyleENS_4Node11StyleChangeE
-   fun:_ZN7WebCore8Document19updateStyleIfNeededEv
-   fun:_ZN7WebCore8Document26updateStyleForAllDocumentsEv
-   fun:_ZN7WebCore4Node20dispatchGenericEventEN3WTF10PassRefPtrINS_5EventEEE
-   fun:_ZN7WebCore4Node13dispatchEventEN3WTF10PassRefPtrINS_5EventEEE
-   fun:_ZN7WebCore8Document15finishedParsingEv
-   fun:_ZN7WebCore10HTMLParser8finishedEv
-}
-{
    bug_23310
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN7history14HistoryBackend12SetPageTitleERK4GURLRKSbIwSt11char_traitsIwESaIwEE
    fun:_Z16DispatchToMethodIN7history14HistoryBackendEMS1_FvRK4GURLRKSbIwSt11char_traitsIwESaIwEEES2_S8_EvPT_T0_RK6Tuple2IT1_T2_E
    fun:_ZN14RunnableMethodIN7history14HistoryBackendEMS1_FvRK4GURLRKSbIwSt11char_traitsIwESaIwEEE6Tuple2IS2_S8_EE3RunEv
    fun:_ZN11MessageLoop7RunTaskEP4Task
 }
 {
    bug_23313
@@ skipping 75 matching lines @@
    fun:_ZN7WebCore7V8Proxy19initContextIfNeededEv
    fun:_ZN7WebCore7V8Proxy16mainWorldContextEPNS_5FrameE
    fun:_ZN7WebCore16ScriptController8evaluateERKNS_16ScriptSourceCodeE
    fun:_ZN7WebCore16ScriptController13executeScriptERKNS_16ScriptSourceCodeE
    fun:_ZN7WebCore13HTMLTokenizer15scriptExecutionERKNS_16ScriptSourceCodeENS0_5StateE
    fun:_ZN7WebCore13HTMLTokenizer13scriptHandlerENS0_5StateE
    fun:_ZN7WebCore13HTMLTokenizer16parseNonHTMLTextERNS_15SegmentedStringENS0_5StateE
    fun:_ZN7WebCore13HTMLTokenizer8parseTagERNS_15SegmentedStringENS0_5StateE
    fun:_ZN7WebCore13HTMLTokenizer5writeERKNS_15SegmentedStringEb
 }