[debug,api] Do not use embedder field for debug context id.

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 7e9725075e4741cd7a81cb449ca67223f1fe629c..9bf89e2e12066f9be1d6e92e8b9c3a9f15128f78 100644
--- a/src/wasm/wasm-module.cc
+++ b/src/wasm/wasm-module.cc
@@ -135,8 +135,7 @@ Handle<Script> CreateWasmScript(Isolate* isolate,
                                 const ModuleWireBytes& wire_bytes) {
   Handle<Script> script =
       isolate->factory()->NewScript(isolate->factory()->empty_string());
-  FixedArray* array = isolate->native_context()->embedder_data();
-  script->set_context_data(array->get(v8::Context::kDebugIdIndex));
+  script->set_context_data(isolate->native_context()->debug_context_id());
   script->set_type(Script::TYPE_WASM);
 
   int hash = StringHasher::HashSequentialString(