[wasm] Handle no memory case when memory is exported

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 0e8054a9d895657d8db9aa561d6e9c6cf9a9a96f..a9bed84e47222581b8326aa227303ba6fb089c46 100644
--- a/src/wasm/wasm-module.cc
+++ b/src/wasm/wasm-module.cc
@@ -1953,7 +1953,10 @@ class InstantiationHelper {
             // If there was no imported WebAssembly.Memory object, create one.
             Handle<JSArrayBuffer> buffer(instance->memory_buffer(), isolate_);
             memory_object = WasmMemoryObject::New(
-                isolate_, buffer,
+                isolate_,
+                (instance->has_memory_buffer())
+                    ? handle(instance->memory_buffer())
+                    : Handle<JSArrayBuffer>::null(),
                 (module_->max_mem_pages != 0) ? module_->max_mem_pages : -1);
             instance->set_memory_object(*memory_object);
           } else {