XFA: Fix a crashier in SetFocus()

public/fpdf_formfill.h

Index: public/fpdf_formfill.h
diff --git a/public/fpdf_formfill.h b/public/fpdf_formfill.h
index b3bbb9280c0e4d82ee0cd120761c29b4d5e28f86..45c7e52c0c49621d8c8890167301829ce537adcd 100644
--- a/public/fpdf_formfill.h
+++ b/public/fpdf_formfill.h
@@ -709,7 +709,7 @@ typedef struct _FPDF_FORMFILLINFO {
     * Method: FFI_DisplayCaret
     *           This method will show the caret at specified position.
     * Interface Version:
-    *           1
+    *           2
     * Implementation Required:
     *           yes
     * Parameters:
@@ -739,7 +739,7 @@ typedef struct _FPDF_FORMFILLINFO {
   * Method: FFI_GetCurrentPageIndex
   *           This method will get the current page index.
   * Interface Version:
-  *           1
+  *           2
   * Implementation Required:
   *           yes
   * Parameters:
@@ -756,7 +756,7 @@ typedef struct _FPDF_FORMFILLINFO {
   * Method: FFI_SetCurrentPage
   *           This method will set the current page.
   * Interface Version:
-  *           1
+  *           2
   * Implementation Required:
   *           yes
   * Parameters:
@@ -775,7 +775,7 @@ typedef struct _FPDF_FORMFILLINFO {
   * Method: FFI_GotoURL
   *           This method will link to the specified URL.
   * Interface Version:
-  *           1
+  *           2
   * Implementation Required:
   *           no
   * Parameters:
@@ -794,7 +794,7 @@ typedef struct _FPDF_FORMFILLINFO {
   * Method: FFI_GetPageViewRect
   *           This method will get the current page view rectangle.
   * Interface Version:
-  *           1
+  *           2
   * Implementation Required:
   *           yes
   * Parameters:
@@ -822,7 +822,7 @@ typedef struct _FPDF_FORMFILLINFO {
   * Method: FFI_PopupMenu
   *           This method will track the right context menu for XFA fields.
   * Interface Version:
-  *           1
+  *           2
   * Implementation Required:
   *           yes
   * Parameters:
@@ -845,7 +845,7 @@ typedef struct _FPDF_FORMFILLINFO {
   * Method: FFI_OpenFile
   *           This method will open the specified file with the specified mode.
   * Interface Version
-  *           1
+  *           2
   * Implementation Required:
   *           yes
   * Parameters:
@@ -868,7 +868,7 @@ typedef struct _FPDF_FORMFILLINFO {
   *           This method will email the specified file stream to the specified
   *contacter.
   * Interface Version:
-  *           1
+  *           2
   * Implementation Required:
   *           yes
   * Parameters:
@@ -899,7 +899,7 @@ typedef struct _FPDF_FORMFILLINFO {
   *           This method will get upload the specified file stream to the
   *specified URL.
   * Interface Version:
-  *           1
+  *           2
   * Implementation Required:
   *           yes
   * Parameters:
@@ -920,7 +920,7 @@ typedef struct _FPDF_FORMFILLINFO {
   * Method: FFI_GetPlatform
   *           This method will get the current platform.
   * Interface Version:
-  *           1
+  *           2
   * Implementation Required:
   *           yes
   * Parameters:
@@ -940,7 +940,7 @@ typedef struct _FPDF_FORMFILLINFO {
   * Method: FFI_GetLanguage
   *           This method will get the current language.
   * Interface Version:
-  *           1
+  *           2
   * Implementation Required:
   *           yes
   * Parameters:
@@ -960,7 +960,7 @@ typedef struct _FPDF_FORMFILLINFO {
   * Method: FFI_DownloadFromURL
   *           This method will download the specified file from the URL.
   * Interface Version:
-  *           1
+  *           2
   * Implementation Required:
   *           yes
   * Parameters:
@@ -975,7 +975,7 @@ typedef struct _FPDF_FORMFILLINFO {
   * Method: FFI_PostRequestURL
   *           This method will post the request to the server URL.
   * Interface Version:
-  *           1
+  *           2
   * Implementation Required:
   *           yes
   * Parameters:
@@ -998,7 +998,7 @@ typedef struct _FPDF_FORMFILLINFO {
   * Method: FFI_PutRequestURL
   *           This method will put the request to the server URL.
   * Interface Version:
-  *           1
+  *           2
   * Implementation Required:
   *           yes
   * Parameters: