Make Error.prototype.toString spec compliant; and fix various side-effect-free error printing metho…

src/objects.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_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 1153 matching lines @@
                                                       Handle<Object> input);
 
   // ES6 section 7.1.15 ToLength
   MUST_USE_RESULT static MaybeHandle<Object> ToLength(Isolate* isolate,
                                                       Handle<Object> input);
 
   // ES6 section 7.3.9 GetMethod
   MUST_USE_RESULT static MaybeHandle<Object> GetMethod(
       Handle<JSReceiver> receiver, Handle<Name> name);
 
+  // Check whether |object| is an instance of Error or NativeError.
+  static bool IsErrorObject(Isolate* isolate, Handle<Object> object);
+
   // ES6 section 12.5.6 The typeof Operator
   static Handle<String> TypeOf(Isolate* isolate, Handle<Object> object);
 
   // ES6 section 12.6 Multiplicative Operators
   MUST_USE_RESULT static MaybeHandle<Object> Multiply(
       Isolate* isolate, Handle<Object> lhs, Handle<Object> rhs,
       Strength strength = Strength::WEAK);
   MUST_USE_RESULT static MaybeHandle<Object> Divide(
       Isolate* isolate, Handle<Object> lhs, Handle<Object> rhs,
       Strength strength = Strength::WEAK);
@@ skipping 9499 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_