[errors] Improve NotGeneric error message

src/messages.h

 // Copyright 2006-2008 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.
 
 // The infrastructure used for (localized) message reporting in V8.
 //
 // Note: there's a big unresolved issue about ownership of the data
 // structures used by this framework.
 
 #ifndef V8_MESSAGES_H_
@@ skipping 324 matching lines @@
   T(NonObjectInInstanceOfCheck,                                                \
     "Right-hand side of 'instanceof' is not an object")                        \
   T(NonObjectPropertyLoad, "Cannot read property '%' of %")                    \
   T(NonObjectPropertyStore, "Cannot set property '%' of %")                    \
   T(NoSetterInCallback, "Cannot set property % of % which has only a getter")  \
   T(NotAnIterator, "% is not an iterator")                                     \
   T(NotAPromise, "% is not a promise")                                         \
   T(NotConstructor, "% is not a constructor")                                  \
   T(NotDateObject, "this is not a Date object.")                               \
   T(NotIntlObject, "% is not an i18n object.")                                 \
-  T(NotGeneric, "% is not generic")                                            \
+  T(NotGeneric, "% requires that 'this' be a %")                               \
   T(NotIterable, "% is not iterable")                                          \
   T(NotPropertyName, "% is not a valid property name")                         \
   T(NotTypedArray, "this is not a typed array.")                               \
   T(NotSuperConstructor, "Super constructor % of % is not a constructor")      \
   T(NotSuperConstructorAnonymousClass,                                         \
     "Super constructor % of anonymous class is not a constructor")             \
   T(NotIntegerSharedTypedArray, "% is not an integer shared typed array.")     \
   T(NotInt32SharedTypedArray, "% is not an int32 shared typed array.")         \
   T(ObjectGetterExpectingFunction,                                             \
     "Object.prototype.__defineGetter__: Expecting function")                   \
@@ skipping 396 matching lines @@
                                         const MessageLocation* loc,
                                         Handle<Object> message_obj,
                                         v8::Local<v8::Value> api_exception_obj);
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_MESSAGES_H_