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

src/base/atomic-utils.h

Index: src/base/atomic-utils.h
diff --git a/src/base/atomic-utils.h b/src/base/atomic-utils.h
index f40853c587b09a0dd3c37473e7963ef676d17db6..f4f43fc8173d2e349b0fe005445ff73ca2a501c0 100644
--- a/src/base/atomic-utils.h
+++ b/src/base/atomic-utils.h
@@ -31,7 +31,9 @@ class AtomicNumber {
         &value_, -static_cast<base::AtomicWord>(decrement)));
   }
 
-  V8_INLINE T Value() { return static_cast<T>(base::Acquire_Load(&value_)); }
+  V8_INLINE T Value() const {
+    return static_cast<T>(base::Acquire_Load(&value_));
+  }
 
   V8_INLINE void SetValue(T new_value) {
     base::Release_Store(&value_, static_cast<base::AtomicWord>(new_value));