sw: revert type changes in SwFrm subclass destructors

These should be unnecessary now with DestroyImpl() and might break stuff.

Reverts commits 5a934b2c and
db2c0dc7.

Change-Id: Ida880dfed9fa6445b3530e2c4788fd4974c8f9c7

sw/source/core/layout/fly.cxx

@@ -269,10 +269,6 @@ void SwFlyFrm::DestroyImpl()
 
     FinitDrawObj();
 
-    // Hack to make sure code called from base ~SwLayoutFrm does not interpret
-    // this as a SwFlyFrm (which it no longer is by then):
-    mnFrmType = FRM_UNUSED;
-
     SwLayoutFrm::DestroyImpl();
 }
 

sw/source/core/layout/pagechg.cxx

@@ -264,10 +264,6 @@ void SwPageFrm::DestroyImpl()
         }
     }
 
-    // Hack to make sure code called from base ~SwFtnBossFrm does not interpret
-    // this as a SwPageFrm (which it no longer is by then):
-    mnFrmType = FRM_UNUSED;
-
     SwFtnBossFrm::DestroyImpl();
 }