Add a test for OptimizingCompileDispatcher::Flush's non-blocking behavior

src/compiler.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_H_
 #define V8_COMPILER_H_
 
 #include <memory>
 
 #include "src/allocation.h"
@@ skipping 136 matching lines @@
 
 // A base class for compilation jobs intended to run concurrent to the main
 // thread. The job is split into three phases which are called in sequence on
 // different threads and with different limitations:
 //  1) PrepareJob:   Runs on main thread. No major limitations.
 //  2) ExecuteJob:   Runs concurrently. No heap allocation or handle derefs.
 //  3) FinalizeJob:  Runs on main thread. No dependency changes.
 //
 // Each of the three phases can either fail or succeed. The current state of
 // the job can be checked using {state()}.
-class CompilationJob {
+class V8_EXPORT_PRIVATE CompilationJob {
  public:
   enum Status { SUCCEEDED, FAILED };
   enum class State {
     kReadyToPrepare,
     kReadyToExecute,
     kReadyToFinalize,
     kSucceeded,
     kFailed,
   };
 
@@ skipping 65 matching lines @@
       state_ = State::kFailed;
     }
     return status;
   }
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_H_