Worklet: Move Worklet::Initialize() into ThreadedWorklet for cleanup

third_party/WebKit/Source/core/workers/MainThreadWorklet.cpp

Index: third_party/WebKit/Source/core/workers/MainThreadWorklet.cpp
diff --git a/third_party/WebKit/Source/core/workers/MainThreadWorklet.cpp b/third_party/WebKit/Source/core/workers/MainThreadWorklet.cpp
index 1c7e06f83015b15769eed29befdbf54df2911f3f..b3ffe3bec9481ff04fadb12b4fb0ac8651013d69 100644
--- a/third_party/WebKit/Source/core/workers/MainThreadWorklet.cpp
+++ b/third_party/WebKit/Source/core/workers/MainThreadWorklet.cpp
@@ -46,9 +46,6 @@ ScriptPromise MainThreadWorklet::addModule(ScriptState* script_state,
                           kSyntaxError, "'" + url + "' is not a valid URL."));
   }
 
-  if (!IsInitialized())
-    Initialize();
-
   int32_t request_id = GetNextRequestId();
   ScriptPromiseResolver* resolver = ScriptPromiseResolver::Create(script_state);
   ScriptPromise promise = resolver->Promise();
@@ -74,6 +71,7 @@ void MainThreadWorklet::DidFetchAndInvokeScript(int32_t request_id,
 void MainThreadWorklet::ContextDestroyed(ExecutionContext* execution_context) {
   DCHECK(IsMainThread());
   resolver_map_.clear();
+  GetWorkletGlobalScopeProxy()->TerminateWorkletGlobalScope();
   Worklet::ContextDestroyed(execution_context);
 }