Fix a double free in CPDFSDK_PageView::IsValidAnnot().
Fix a double free in CPDFSDK_PageView::IsValidAnnot().

BUG=635848

Review-Url: https://codereview.chromium.org/2242213004

DrAlexx/pdfium,DrAlexx/pdfium,DrAlexx/pdfium,DrAlexx/pdfium