[wasm] With possible nondeterminism the fuzzer should not check traps

The non-determinism of NaNs does not only affect the result of the test
function, it also affects the traps that are thrown.

R=titzer@chromium.org, eholk@chromium.org
BUG=v8:5924

Review-Url: https://codereview.chromium.org/2671813004
Cr-Commit-Position: refs/heads/master@{#42973}

test/fuzzer/wasm-code.cc

@@ -136,7 +136,8 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
         i_isolate, instance, &compiler_thrower, "main", arraysize(arguments),
         arguments, v8::internal::wasm::ModuleOrigin::kWasmOrigin);
   }
-  if (result_interpreted == bit_cast<int32_t>(0xdeadbeef)) {
+  if (result_interpreted == bit_cast<int32_t>(0xdeadbeef) &&
+      !possible_nondeterminism) {
     CHECK(i_isolate->has_pending_exception());
     i_isolate->clear_pending_exception();
   } else {