Limit input size in pdf_fx_date_helpers_fuzzer.

Longer inputs are unlikely to find anything but will cause
timeouts in debug builds.

Bug: chromium:947780
Change-Id: I811d6f70ff38c38a1385a7ff4ff1bed0775ba706
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/52730
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

testing/fuzzers/pdf_fx_date_helpers_fuzzer.cc

diff --git a/testing/fuzzers/pdf_fx_date_helpers_fuzzer.cc b/testing/fuzzers/pdf_fx_date_helpers_fuzzer.cc
index ff81c47..e31decc 100644
--- a/testing/fuzzers/pdf_fx_date_helpers_fuzzer.cc
+++ b/testing/fuzzers/pdf_fx_date_helpers_fuzzer.cc
@@ -10,7 +10,7 @@
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   auto* short_data = reinterpret_cast<const unsigned short*>(data);
   size_t short_size = size / sizeof(unsigned short);
-  if (short_size > 2) {
+  if (short_size > 2 && short_size < 8192) {
     double ignore;
     size_t short_len1 = short_size / 2;
     size_t short_len2 = short_size - short_len1;