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

src/wasm/wasm-module.cc

Index: src/wasm/wasm-module.cc
diff --git a/src/wasm/wasm-module.cc b/src/wasm/wasm-module.cc
index e5173eba092125e14e79ec818d335a9c114c0dde..8f54a1dc8fc1c5f9d619746fd2f9cbd9cf6c0a0e 100644
--- a/src/wasm/wasm-module.cc
+++ b/src/wasm/wasm-module.cc
@@ -745,7 +745,8 @@ Handle<Script> CreateWasmScript(Isolate* isolate,
 
 Handle<JSArrayBuffer> wasm::NewArrayBuffer(Isolate* isolate, size_t size,
                                            bool enable_guard_regions) {
-  if (size > (kV8MaxWasmMemoryPages * WasmModule::kPageSize)) {
+  if (size > (static_cast<uint32_t>(FLAG_wasm_max_mem_pages) *
+              WasmModule::kPageSize)) {
     // TODO(titzer): lift restriction on maximum memory allocated here.
     return Handle<JSArrayBuffer>::null();
   }
@@ -1767,7 +1768,7 @@ class WasmInstanceBuilder {
 
   // Allocate memory for a module instance as a new JSArrayBuffer.
   Handle<JSArrayBuffer> AllocateMemory(uint32_t min_mem_pages) {
-    if (min_mem_pages > kV8MaxWasmMemoryPages) {
+    if (min_mem_pages > static_cast<uint32_t>(FLAG_wasm_max_mem_pages)) {
       thrower_->RangeError("Out of memory: wasm memory too large");
       return Handle<JSArrayBuffer>::null();
     }
@@ -2198,7 +2199,7 @@ uint32_t GetMaxInstanceMemorySize(Isolate* isolate,
   isolate->counters()->wasm_max_mem_pages_count()->AddSample(
       compiled_max_pages);
   if (compiled_max_pages != 0) return compiled_max_pages;
-  return kV8MaxWasmMemoryPages;
+  return static_cast<uint32_t>(FLAG_wasm_max_mem_pages);
 }
 
 Handle<JSArrayBuffer> GrowMemoryBuffer(Isolate* isolate,
@@ -2216,7 +2217,8 @@ Handle<JSArrayBuffer> GrowMemoryBuffer(Isolate* isolate,
          std::numeric_limits<uint32_t>::max());
   uint32_t new_size = old_size + pages * WasmModule::kPageSize;
   if (new_size <= old_size || max_pages * WasmModule::kPageSize < new_size ||
-      kV8MaxWasmMemoryPages * WasmModule::kPageSize < new_size) {
+      static_cast<uint32_t>(FLAG_wasm_max_mem_pages) * WasmModule::kPageSize <
+          new_size) {
     return Handle<JSArrayBuffer>::null();
   }