Fix FPE in XFACodecFuzzer

This is a div by 0 issue

BUG=chromium:779890

Change-Id: I91ca2969ffe52fb486b1fab32abc8609cd6567a2
Reviewed-on: https://pdfium-review.googlesource.com/17250
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>

testing/libfuzzer/xfa_codec_fuzzer.h

diff --git a/testing/libfuzzer/xfa_codec_fuzzer.h b/testing/libfuzzer/xfa_codec_fuzzer.h
index 9a1230d..96074fe 100644
--- a/testing/libfuzzer/xfa_codec_fuzzer.h
+++ b/testing/libfuzzer/xfa_codec_fuzzer.h
@@ -39,7 +39,8 @@
 
     // Skipping very large images, since they will take a long time and may lead
     // to OOM.
-    if (decoder->GetWidth() > kXFACodecFuzzerPixelLimit / decoder->GetHeight())
+    if (decoder->GetHeight() != 0 &&
+        decoder->GetWidth() > kXFACodecFuzzerPixelLimit / decoder->GetHeight())
       return 0;
 
     auto bitmap = pdfium::MakeRetain<CFX_DIBitmap>();