found a tiny bug, possible uninitialized variable. fixed it along with work for:

moved content-specific data and methods from nsIWebShell to appropriate content viewer interface
no bug number, this is for webshell redesign work
r=rickg, travis

layout/base/nsPresContext.cpp

@@ -77,6 +77,7 @@ nsPresContext::nsPresContext()
   mWidgetRenderingMode = eWidgetRendering_Gfx; 
 
   mLookAndFeel = nsnull;
+  mShell = nsnull;
 
 #ifdef _WIN32
   // XXX This needs to be elsewhere, e.g., part of nsIDeviceContext

layout/base/src/nsPresContext.cpp

@@ -77,6 +77,7 @@ nsPresContext::nsPresContext()
   mWidgetRenderingMode = eWidgetRendering_Gfx; 
 
   mLookAndFeel = nsnull;
+  mShell = nsnull;
 
 #ifdef _WIN32
   // XXX This needs to be elsewhere, e.g., part of nsIDeviceContext