Set the view pointer as NULL after its xfa doc is released

fpdfsdk/src/fpdfxfa/fpdfxfa_doc.cpp

Index: fpdfsdk/src/fpdfxfa/fpdfxfa_doc.cpp
diff --git a/fpdfsdk/src/fpdfxfa/fpdfxfa_doc.cpp b/fpdfsdk/src/fpdfxfa/fpdfxfa_doc.cpp
index d8c08cc2a5c549ffeb6a2ec7fd996c920d348fd1..8a7db3f8586f2be91dfbbbd42b56270b1382be6c 100644
--- a/fpdfsdk/src/fpdfxfa/fpdfxfa_doc.cpp
+++ b/fpdfsdk/src/fpdfxfa/fpdfxfa_doc.cpp
@@ -81,6 +81,7 @@ CPDFXFA_Document::~CPDFXFA_Document()
 				pDocHandler->CloseDoc(m_pXFADoc);

[Tom Sepez, 2015/02/17 19:14:08]

nit: can we make a helper method to do these 4 steps?  It looks like we do the
same thing in several places?

 				pDocHandler->ReleaseDoc(m_pXFADoc);
 				m_pXFADoc = NULL;
+				m_pXFADocView = NULL;
 			}	
 		}
 	}
@@ -132,6 +133,7 @@ FX_BOOL CPDFXFA_Document::LoadXFADoc()
 					pDocHandler->CloseDoc(m_pXFADoc);
 					pDocHandler->ReleaseDoc(m_pXFADoc);
 					m_pXFADoc = NULL;
+					m_pXFADocView = NULL;
 
 					SetLastError(FPDF_ERR_XFALOAD);
 					return FALSE;
@@ -152,6 +154,7 @@ FX_BOOL CPDFXFA_Document::LoadXFADoc()
 					pDocHandler->CloseDoc(m_pXFADoc);
 					pDocHandler->ReleaseDoc(m_pXFADoc);
 					m_pXFADoc = NULL;
+					m_pXFADocView = NULL;
 
 					SetLastError(FPDF_ERR_XFALAYOUT);
 					return FALSE;