Bug 251056

The fast/speechsynthesis/speech-synthesis-real-client-version.html crashes. Its backtrace is like the following. #0 0x00007ffff1ecbdd8 in WTF::String::tryGetUTF8(WTF::ConversionMode) const () from target:/app/webkit/WebKitBuild/Release/lib/libjavascriptcoregtk-4.1.so.0 #1 0x00007ffff1ecbea0 in WTF::String::utf8(WTF::ConversionMode) const () from target:/app/webkit/WebKitBuild/Release/lib/libjavascriptcoregtk-4.1.so.0 #2 0x00007ffff51985ea in webKitFliteSrcSetUtterance(_WebKitFliteSrc*, WTF::String const&, WebCore::PlatformSpeechSynthesisVoice const&) () from target:/app/webkit/WebKitBuild/Release/lib/libwebkit2gtk-4.1.so.0 #3 0x00007ffff51914e8 in WebCore::GstSpeechSynthesisWrapper::speakUtterance(WTF::RefPtr<WebCore::PlatformSpeechSynthesisUtterance, WTF::RawPtrTraits<WebCore::PlatformSpeechSynthesisUtterance>, WTF::DefaultRefDerefTraits<WebCore::PlatformSpeechSynthesisUtterance> >&&) [clone .part.0] () from target:/app/webkit/WebKitBuild/Release/lib/libwebkit2gtk-4.1.so.0 #4 0x00007ffff51923f5 in WebCore::PlatformSpeechSynthesizer::speak(WTF::RefPtr<WebCore::PlatformSpeechSynthesisUtterance, WTF::RawPtrTraits<WebCore::PlatformSpeechSynthesisUtterance>, WTF::DefaultRefDerefTraits<WebCore::PlatformSpeechSynthesisUtterance> >&&) () from target:/app/webkit/WebKitBuild/Release/lib/libwebkit2gtk-4.1.so.0 #5 0x00007ffff5f5f312 in WebCore::SpeechSynthesis::startSpeakingImmediately(WebCore::SpeechSynthesisUtterance&) () from target:/app/webkit/WebKitBuild/Release/lib/libwebkit2gtk-4.1.so.0 #6 0x00007ffff5b39f98 in WebCore::jsSpeechSynthesisPrototypeFunction_speak(JSC::JSGlobalObject*, JSC::CallFrame*) () from target:/app/webkit/WebKitBuild/Release/lib/libwebkit2gtk-4.1.so.0 #7 0x00007fff90008038 in ?? () #8 0x00007fffffffc180 in ?? () #9 0x00007ffff093a5e4 in js_trampoline_op_call () from target:/app/webkit/WebKitBuild/Release/lib/libjavascriptcoregtk-4.1.so.0 #10 0x0000000000000000 in ?? ()