Bug 1546329 - Remove dead skins code. r=bzbarsky

browser/base/content/test/performance/browser_windowopen.js

chrome/nsChromeRegistry.cpp

chrome/nsChromeRegistry.h

chrome/nsChromeRegistryChrome.cpp

chrome/nsChromeRegistryChrome.h

chrome/nsChromeRegistryContent.cpp

chrome/nsChromeRegistryContent.h

chrome/nsIChromeRegistry.idl

chrome/nsIToolkitChromeRegistry.idl

dom/base/Document.cpp

dom/base/Document.h

dom/xbl/nsBindingManager.cpp

dom/xbl/nsBindingManager.h

dom/xul/nsXULPrototypeCache.cpp

dom/xul/nsXULPrototypeCache.h

image/imgLoader.cpp

layout/base/PresShell.cpp

layout/style/nsLayoutStylesheetCache.cpp

toolkit/content/tests/chrome/RegisterUnregisterChrome.js

toolkit/xre/nsAppRunner.cpp