[wasm] Change the constant kV8MaxWasmMemoryPages to a command line flag.

test/fuzzer/wasm-asmjs.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 
 #include "include/v8.h"
 #include "src/factory.h"
 #include "src/isolate-inl.h"
 #include "src/isolate.h"
 #include "src/objects-inl.h"
 #include "src/objects.h"
 #include "src/wasm/wasm-module.h"
 #include "test/common/wasm/wasm-module-runner.h"
 #include "test/fuzzer/fuzzer-support.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  unsigned int flag_value = v8::internal::FLAG_wasm_max_mem_pages;
+  v8::internal::FLAG_wasm_max_mem_pages = 32;
   v8_fuzzer::FuzzerSupport* support = v8_fuzzer::FuzzerSupport::Get();
   v8::Isolate* isolate = support->GetIsolate();
   v8::internal::Isolate* i_isolate =
       reinterpret_cast<v8::internal::Isolate*>(isolate);
 
   // Clear any pending exceptions from a prior run.
   if (i_isolate->has_pending_exception()) {
     i_isolate->clear_pending_exception();
   }
 
   v8::Isolate::Scope isolate_scope(isolate);
   v8::HandleScope handle_scope(isolate);
   v8::Context::Scope context_scope(support->GetContext());
   v8::TryCatch try_catch(isolate);
   v8::internal::wasm::testing::SetupIsolateForWasmModule(i_isolate);
   v8::internal::wasm::testing::CompileAndRunWasmModule(
       i_isolate, data, data + size,
       v8::internal::wasm::ModuleOrigin::kAsmJsOrigin);
+  v8::internal::FLAG_wasm_max_mem_pages = flag_value;
   return 0;
 }