Calc: edit engine could be accessed after being destroyed

ScTabView <---------------- ScTabViewShell
+ScViewData                 +ScInputHandler
   +EditView[4]                +EditEngine
                                +ImpEditEngine
                                   +vector<pointer<EditView>>

On tab view shell destruction:
~ScTabViewShell -> ~ScTabView -> ScViewData::KillEditView ->
EditEngine::RemoveView

but it occurs after the following:
~ScTabViewShell -> ~ScInputHandler -> ~EditEngine

since data members are destroyed before ancestor classes.

Change-Id: Ida56b8009c0d8a3cd23952259d78318e96ae5124
Reviewed-on: https://gerrit.libreoffice.org/29409Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Marco Cecchetti <mrcekets@gmail.com>

sc/source/ui/app/inputhdl.cxx

@@ -661,14 +661,14 @@ ScInputHandler::~ScInputHandler()
     if ( pInputWin && pInputWin->GetInputHandler() == this )
         pInputWin->SetInputHandler( nullptr );
 
-    delete pRangeFindList;
-    delete pEditDefaults;
-    delete pEngine;
-    delete pLastState;
-    delete pDelayTimer;
-    delete pColumnData;
-    delete pFormulaData;
-    delete pFormulaDataPara;
+    delete pRangeFindList;     pRangeFindList = nullptr;
+    delete pEditDefaults;      pEditDefaults = nullptr;
+    delete pEngine;            pEngine = nullptr;
+    delete pLastState;         pLastState = nullptr;
+    delete pDelayTimer;        pDelayTimer = nullptr;
+    delete pColumnData;        pColumnData = nullptr;
+    delete pFormulaData;       pFormulaData = nullptr;
+    delete pFormulaDataPara;   pFormulaDataPara = nullptr;
 }
 
 void ScInputHandler::SetRefScale( const Fraction& rX, const Fraction& rY )

sc/source/ui/view/viewdata.cxx

@@ -1435,11 +1435,16 @@ void ScViewData::ResetEditView()
 
 void ScViewData::KillEditView()
 {
+    EditEngine* pEngine = nullptr;
     for (sal_uInt16 i=0; i<4; i++)
         if (pEditView[i])
         {
             if (bEditActive[i])
-                pEditView[i]->GetEditEngine()->RemoveView(pEditView[i]);
+            {
+                pEngine = pEditView[i]->GetEditEngine();
+                if (pEngine)
+                    pEngine->RemoveView(pEditView[i]);
+            }
             delete pEditView[i];
             pEditView[i] = nullptr;
         }