Resolves: fdo#88594 crash on F1 with local help

regression from

commit 1049511c
Date:   Tue Jan 13 21:43:27 2015 +0900
    infobar: add buttons one by one with addButton

Change-Id: Icf758a9671191836bbe5bc7ca7d978574cb74479

sfx2/source/view/sfxbasecontroller.cxx

@@ -1448,10 +1448,13 @@ void SfxBaseController::ShowInfoBars( )
                 {
                     // Get the Frame and show the InfoBar if not checked out
                     SfxViewFrame* pViewFrame = m_pData->m_pViewShell->GetFrame();
-                    PushButton* pBtn = new PushButton( &pViewFrame->GetWindow(), SfxResId( BT_CHECKOUT ) );
-                    pBtn->SetClickHdl( LINK( this, SfxBaseController, CheckOutHandler ) );
                     SfxInfoBarWindow* pInfoBar = pViewFrame->AppendInfoBar( "checkout", SfxResId( STR_NONCHECKEDOUT_DOCUMENT ) );
-                    pInfoBar->addButton(pBtn);
+                    if (pInfoBar)
+                    {
+                        PushButton* pBtn = new PushButton( &pViewFrame->GetWindow(), SfxResId( BT_CHECKOUT ) );
+                        pBtn->SetClickHdl( LINK( this, SfxBaseController, CheckOutHandler ) );
+                        pInfoBar->addButton(pBtn);
+                    }
                 }
             }
         }

sfx2/source/view/viewfrm.cxx

@@ -1380,10 +1380,12 @@ void SfxViewFrame::Notify( SfxBroadcaster& /*rBC*/, const SfxHint& rHint )
                 else
                 {
                     SfxInfoBarWindow* pInfoBar = AppendInfoBar("readonly", SfxResId(STR_READONLY_DOCUMENT));
-
-                    PushButton* pBtn = new PushButton( &GetWindow(), SfxResId(BT_READONLY_EDIT));
-                    pBtn->SetClickHdl(LINK(this, SfxViewFrame, SwitchReadOnlyHandler));
-                    pInfoBar->addButton(pBtn);
+                    if (pInfoBar)
+                    {
+                        PushButton* pBtn = new PushButton( &GetWindow(), SfxResId(BT_READONLY_EDIT));
+                        pBtn->SetClickHdl(LINK(this, SfxViewFrame, SwitchReadOnlyHandler));
+                        pInfoBar->addButton(pBtn);
+                    }
                 }
 
                 break;