开刀的类名叫 PluginWidgetIOS，利用lldb可以得到：

(lldb) image lookup -r -s PluginWidgetIOS
7 symbols match the regular expression 'PluginWidgetIOS' in /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator6.1.sdk/System/Library/PrivateFrameworks/WebKit.framework/WebKit:
        Address: WebKit[0x0003a5a0] (WebKit.__TEXT.__text + 231680)
        Summary: WebKit`PluginWidgetIOS::~PluginWidgetIOS()        Address: WebKit[0x0003a5b0] (WebKit.__TEXT.__text + 231696)
        Summary: WebKit`PluginWidgetIOS::~PluginWidgetIOS()        Address: WebKit[0x0003a6f0] (WebKit.__TEXT.__text + 232016)
        Summary: WebKit`PluginWidgetIOS::platformLayer() const        Address: WebKit[0x0003a750] (WebKit.__TEXT.__text + 232112)
        Summary: WebKit`PluginWidgetIOS::willProvidePluginLayer() const        Address: WebKit[0x0003a7b0] (WebKit.__TEXT.__text + 232208)
        Summary: WebKit`PluginWidgetIOS::attachPluginLayer()        Address: WebKit[0x0003a810] (WebKit.__TEXT.__text + 232304)
        Summary: WebKit`PluginWidgetIOS::detachPluginLayer()        Address: WebKit[0x001335e0] (WebKit.__DATA.__data + 560)
        Summary: vtable for PluginWidgetIOS

其中有用的信息是：

Address: WebKit[0x001335e0] (WebKit.__DATA.__data + 560)
        Summary: vtable for PluginWidgetIOS

用IDA打开WebCore的静态库，goto（快捷键g） vtable所在的地址 0x1335e0，可以看到：

__data:001335E0 ; `vtable for'PluginWidgetIOS
__data:001335E0 __ZTV15PluginWidgetIOS db    0          ; DATA XREF: __nl_symbol_ptr:__ZTV15PluginWidgetIOS_ptr