Fix ooms and timeouts on large inputs for blink_http_parsers_fuzzer.

Most web servers restrict http headers to 8-48 Kb. Restrict the maximum
size for fuzzer efficiency and avoid ooms and timeouts on large inputs.
See also:
https://chromium.googlesource.com/chromium/src/testing/libfuzzer/+/HEAD/getting_started.md#improving-your-fuzz-target

R=tkent@chromium.org

Bug: 830145
Change-Id: Ib577fb88952207b2c6f00643fda343d3e1254514
Reviewed-on: https://chromium-review.googlesource.com/c/1329674Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Abhishek Arya <inferno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607138}

third_party/blink/renderer/platform/network/http_parsers_fuzzer.cc

@@ -12,6 +12,10 @@
 #include "third_party/blink/renderer/platform/wtf/text/atomic_string.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  // Larger inputs trigger OOMs, timeouts and slow units.
+  if (size > 65536)
+    return 0;
+
   static blink::BlinkFuzzerTestSupport test_support;
 
   blink::CommaDelimitedHeaderSet set;