Issue #4692 - Rewrite I/O tasks to avoid engine self-reference

src/JsEngineInternal.h

 
 #if !defined(ADBLOCK_PLUS_JS_ENGINE_INTERNAL_H)
 #define ADBLOCK_PLUS_JS_ENGINE_INTERNAL_H
 
 #include <AdblockPlus/JsEngine.h>
 #include <v8.h>
 #include <array>
 #include "AllocatedArray.h"
 #include "V8Upgrade.h"
 
@@ skipping 115 matching lines @@
   /**
    * Call a function with an arbitrary object as "this"
    *
    * Defined as a member of the engine class as part of v8 upgrade path.
    * Newer versions of v8 require a context argument for `v8::Function::Call()`.
    */
   v8::Local<v8::Value> ApplyFunction(
     v8::Local<v8::Object> thisObject,
     v8::Local<v8::Function> func,
     AllocatedArray<v8::Local<v8::Value>> args);
+
+  /**
+   * Convert a standard string to a v8 string within the present isolate.
+   */
+  v8::Local<v8::String> ToV8String(const std::string& s);
 };
 
 /**
  * Sentry class setting up a multi-threaded v8 usage environment.
  *
  * The engine has the responsibility for maintaining an isolate and a context.
  * This class maintains the following:
  * - v8 lock to ensure single-threaded JS evaluation.
  * - v8 scopes for isolate, handle, and scope.
  * - shared_ptr to engine
@@ skipping 16 matching lines @@
    */
   const v8::HandleScope handleScope;
   const v8::Context::Scope contextScope;
 public:
   V8ExecutionScope(JsEngineInternal* engine);
 };
 
 
 
 #endif