[Isolates] Avoid dereferencing Isolate::Current() to check oddball identities...

src/ast.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 849 matching lines @@
     }
     return false;
   }
 
   virtual bool IsLeaf() { return true; }
   virtual bool IsTrivial() { return true; }
   virtual bool IsPrimitive();
   virtual bool IsCritical();
 
   // Identity testers.
-  bool IsNull() const { return handle_.is_identical_to(Factory::null_value()); }
-  bool IsTrue() const { return handle_.is_identical_to(Factory::true_value()); }
+  bool IsNull() const {
+    ASSERT(!handle_.is_null());
+    return handle_->IsNull();
+  }
+  bool IsTrue() const {
+    ASSERT(!handle_.is_null());
+    return handle_->IsTrue();
+  }
   bool IsFalse() const {
-    return handle_.is_identical_to(Factory::false_value());
+    ASSERT(!handle_.is_null());
+    return handle_->IsFalse();
   }
 
   Handle<Object> handle() const { return handle_; }
 
  private:
   Handle<Object> handle_;
 };
 
 
 // Base class for literals that needs space in the corresponding JSFunction.
@@ skipping 1224 matching lines @@
 
   // Holds the result of copying an expression.
   Expression* expr_;
   // Holds the result of copying a statement.
   Statement* stmt_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_AST_H_