[turbofan] Introduce ToBooleanHints on ToBoolean operators.

src/base/flags.h

Index: src/base/flags.h
diff --git a/src/base/flags.h b/src/base/flags.h
index 467ecf67c953dbb810ee69f03109a0279dc939ea..4d9e14e5f913fc8a8b8c9bb6fb88ca55b5150896 100644
--- a/src/base/flags.h
+++ b/src/base/flags.h
@@ -5,6 +5,8 @@
 #ifndef V8_BASE_FLAGS_H_
 #define V8_BASE_FLAGS_H_
 
+#include <cstddef>
+
 #include "src/base/compiler-specific.h"
 
 namespace v8 {
@@ -30,6 +32,13 @@ class Flags final {
       : mask_(static_cast<S>(flag)) {}
   explicit Flags(mask_type mask) : mask_(static_cast<S>(mask)) {}
 
+  bool operator==(flag_type flag) const {
+    return mask_ == static_cast<S>(flag);
+  }
+  bool operator!=(flag_type flag) const {
+    return mask_ != static_cast<S>(flag);
+  }
+
   Flags& operator&=(const Flags& flags) {
     mask_ &= flags.mask_;
     return *this;
@@ -60,6 +69,8 @@ class Flags final {
   operator mask_type() const { return mask_; }
   bool operator!() const { return !mask_; }
 
+  friend size_t hash_value(const Flags& flags) { return flags.mask_; }
+
  private:
   mask_type mask_;
 };