[PerModuleStyleManagement] RTE when module is reloaded.

Steps to reproduce:
1. Compile the app and module.
2. Run the app
3. Click on Load Module
4. Click on Unload Module
5. Click again on Load Module.

Actual Results:
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at mx.styles::StyleProtoChain$/initProtoChainForUIComponentStyleName()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/styles/StyleProtoChain.as:343]
at mx.styles::StyleProtoChain$/initProtoChain()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/styles/StyleProtoChain.as:170]
at mx.core::UIComponent/http://www.adobe.com/2006/flex/mx/internal::initProtoChain()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/UIComponent.as:9764]
at mx.core::UIComponent/regenerateStyleCache()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/UIComponent.as:9827]
at mx.core::Container/regenerateStyleCache()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/Container.as:3692]
at mx.core::UIComponent/set styleName()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/UIComponent.as:6040]
at mx.core::UIComponent/createReferenceOnParentDocument()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/UIComponent.as:10613]
at mx.core::Container/createComponentFromDescriptor()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/Container.as:4291]
at mx.core::Container/createComponentsFromDescriptors()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/Container.as:4105]
at mx.core::Container/createChildren()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/Container.as:3142]
at mx.core::UIComponent/initialize()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/UIComponent.as:6924]
at mx.core::Container/initialize()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/Container.as:3076]
at ModifyCSSDeclarationModule/initialize()
at mx.core::UIComponent/http://www.adobe.com/2006/flex/mx/internal::childAdded()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/UIComponent.as:6816]
at mx.core::Container/http://www.adobe.com/2006/flex/mx/internal::childAdded()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/Container.as:3901]
at mx.core::Container/addChildAt()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/Container.as:2563]
at mx.core::Container/addChild()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/Container.as:2481]
at mx.modules::ModuleLoader/moduleReadyHandler()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/modules/ModuleLoader.as:444]
at flash.events::EventDispatcher/dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at ModuleInfoProxy/moduleEventHandler()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/modules/ModuleManager.as:1159]
at flash.events::EventDispatcher/dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at ModuleInfo/readyHandler()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/modules/ModuleManager.as:803]
at flash.events::EventDispatcher/dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at mx.core::FlexModuleFactory/update()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/FlexModuleFactory.as:438]
at mx.core::FlexModuleFactory/timerHandler()[/Users/gauravj/depot/flex/sdk/frameworks/projects/framework/src/mx/core/FlexModuleFactory.as:670]
at flash.utils::Timer/_timerDispatch()
at flash.utils::Timer/tick()

Expected Results:
No RTE