bug 1241453 - fixup xpcAccessible Intl() methods to not assume mIntl is always an Accessible r=davidb

accessible/xpcom/xpcAccessibleDocument.h

@@ -61,7 +61,14 @@ protected:
   virtual ~xpcAccessibleDocument() {}
 
 private:
-  DocAccessible* Intl() { return mIntl.AsAccessible()->AsDoc(); }
+  DocAccessible* Intl()
+  {
+    if (Accessible* acc = mIntl.AsAccessible()) {
+      return acc->AsDoc();
+    }
+
+    return nullptr;
+  }
 
   void NotifyOfShutdown(Accessible* aAccessible)
   {

accessible/xpcom/xpcAccessibleHyperText.h

@@ -43,7 +43,14 @@ protected:
   virtual ~xpcAccessibleHyperText() {}
 
 private:
-  HyperTextAccessible* Intl() { return mIntl.AsAccessible()->AsHyperText(); }
+  HyperTextAccessible* Intl()
+  {
+    if (Accessible* acc = mIntl.AsAccessible()) {
+      return acc->AsHyperText();
+    }
+
+    return nullptr;
+  }
 
   xpcAccessibleHyperText(const xpcAccessibleHyperText&) = delete;
   xpcAccessibleHyperText& operator =(const xpcAccessibleHyperText&) = delete;

accessible/xpcom/xpcAccessibleImage.h

@@ -34,7 +34,8 @@ protected:
   virtual ~xpcAccessibleImage() {}
 
 private:
-  ImageAccessible* Intl() { return mIntl.AsAccessible()->AsImage(); }
+  ImageAccessible* Intl()
+  { return mIntl.IsAccessible() ? mIntl.AsAccessible()->AsImage() : nullptr; }
 
   xpcAccessibleImage(const xpcAccessibleImage&) = delete;
   xpcAccessibleImage& operator =(const xpcAccessibleImage&) = delete;

accessible/xpcom/xpcAccessibleTable.h

@@ -83,7 +83,8 @@ protected:
   virtual ~xpcAccessibleTable() {}
 
 private:
-  TableAccessible* Intl() { return mIntl.AsAccessible()->AsTable(); }
+  TableAccessible* Intl()
+  { return mIntl.IsAccessible() ? mIntl.AsAccessible()->AsTable() : nullptr; }
 
   xpcAccessibleTable(const xpcAccessibleTable&) = delete;
   xpcAccessibleTable& operator =(const xpcAccessibleTable&) = delete;

accessible/xpcom/xpcAccessibleTableCell.h

@@ -43,7 +43,14 @@ protected:
   virtual ~xpcAccessibleTableCell() {}
 
 private:
-  TableCellAccessible* Intl() { return mIntl.AsAccessible()->AsTableCell(); }
+  TableCellAccessible* Intl()
+  {
+    if (Accessible* acc = mIntl.AsAccessible()) {
+      return acc->AsTableCell();
+    }
+
+    return nullptr;
+}
 
   xpcAccessibleTableCell(const xpcAccessibleTableCell&) = delete;
   xpcAccessibleTableCell& operator =(const xpcAccessibleTableCell&) = delete;