[snapshot] Remove obsolete code modification scope.

R=hpayer@chromium.org
BUG=v8:6792,chromium:787813

Change-Id: I98af2eb8d9e5f3be1bc5807363545a7d89500ef3
Reviewed-on: https://chromium-review.googlesource.com/787712Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49616}

src/snapshot/code-serializer.cc

@@ -243,6 +243,8 @@ MaybeHandle<FixedArray> WasmCompiledModuleSerializer::DeserializeWasmModule(
     return nothing;
   }
 
+  // TODO(6792): No longer needed once WebAssembly code is off heap.
+  CodeSpaceMemoryModificationScope modification_scope(isolate->heap());
   MaybeHandle<WasmCompiledModule> maybe_result =
       ObjectDeserializer::DeserializeWasmCompiledModule(isolate, &scd,
                                                         wire_bytes);
@@ -250,8 +252,6 @@ MaybeHandle<FixedArray> WasmCompiledModuleSerializer::DeserializeWasmModule(
   Handle<WasmCompiledModule> result;
   if (!maybe_result.ToHandle(&result)) return nothing;
 
-  // TODO(6792): No longer needed once WebAssembly code is off heap.
-  CodeSpaceMemoryModificationScope modification_scope(isolate->heap());
   WasmCompiledModule::ReinitializeAfterDeserialization(isolate, result);
   DCHECK(WasmCompiledModule::IsWasmCompiledModule(*result));
   return result;

src/snapshot/object-deserializer.cc

@@ -68,8 +68,6 @@ ObjectDeserializer::DeserializeWasmCompiledModule(
 MaybeHandle<HeapObject> ObjectDeserializer::Deserialize(Isolate* isolate) {
   Initialize(isolate);
 
-  CodeSpaceMemoryModificationScope modification_scope(isolate->heap());
-
   if (!allocator()->ReserveSpace()) return MaybeHandle<HeapObject>();
 
   DCHECK(deserializing_user_code());