Fix a double-free issue in CFX_PathData::~CFX_PathData

In CPDFSDK_InterForm::SubmitFields, the buffer pointed by m_pBuffer is returned
and released by the caller. However, it will be released again in the destructor.

BUG=401580
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/481733002

fpdfsdk/src/fsdk_baseform.cpp

diff --git a/fpdfsdk/src/fsdk_baseform.cpp b/fpdfsdk/src/fsdk_baseform.cpp
index ae3b636..aa87dd5 100644
--- a/fpdfsdk/src/fsdk_baseform.cpp
+++ b/fpdfsdk/src/fsdk_baseform.cpp
@@ -2284,12 +2284,6 @@
 
 	pEnv->JS_docSubmitForm(pBuffer, nBufSize, (FX_LPCWSTR)csDestination);
 	
-	if (bUrlEncoded && pBuffer)
-	{
-		FX_Free(pBuffer);
-		pBuffer = NULL;	
-	}
-
 	return TRUE;
 }