Return MaybeHandle from NewConsString.

src/factory.h

 // Copyright 2014 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_FACTORY_H_
 #define V8_FACTORY_H_
 
 #include "isolate.h"
 
 namespace v8 {
@@ skipping 122 matching lines @@
   // characters of the string are uninitialized. Currently used in regexp code
   // only, where they are pretenured.
   Handle<SeqOneByteString> NewRawOneByteString(
       int length,
       PretenureFlag pretenure = NOT_TENURED);
   Handle<SeqTwoByteString> NewRawTwoByteString(
       int length,
       PretenureFlag pretenure = NOT_TENURED);
 
   // Create a new cons string object which consists of a pair of strings.
-  Handle<String> NewConsString(Handle<String> left,
-                               Handle<String> right);
+  MUST_USE_RESULT MaybeHandle<String> NewConsString(Handle<String> left,
+                                                    Handle<String> right);
 
   Handle<ConsString> NewRawConsString(String::Encoding encoding);
 
   // Create a new sequential string containing the concatenation of the inputs.
   Handle<String> NewFlatConcatString(Handle<String> first,
                                      Handle<String> second);
 
   // Create a new string object which holds a proper substring of a string.
   Handle<String> NewProperSubString(Handle<String> str,
                                     int begin,
@@ skipping 271 matching lines @@
                           Handle<String> message);
 
   Handle<Object> NewTypeError(const char* message,
                               Vector< Handle<Object> > args);
   Handle<Object> NewTypeError(Handle<String> message);
 
   Handle<Object> NewRangeError(const char* message,
                                Vector< Handle<Object> > args);
   Handle<Object> NewRangeError(Handle<String> message);
 
+  Handle<Object> NewInvalidStringLengthError() {
+    return NewRangeError("invalid_string_length",
+                         HandleVector<Object>(NULL, 0));
+  }
+
   Handle<Object> NewSyntaxError(const char* message, Handle<JSArray> args);
   Handle<Object> NewSyntaxError(Handle<String> message);
 
   Handle<Object> NewReferenceError(const char* message,
                                    Vector< Handle<Object> > args);
   Handle<Object> NewReferenceError(const char* message, Handle<JSArray> args);
   Handle<Object> NewReferenceError(Handle<String> message);
 
   Handle<Object> NewEvalError(const char* message,
                               Vector< Handle<Object> > args);
@@ skipping 143 matching lines @@
 
   // Update the map cache in the native context with (keys, map)
   Handle<MapCache> AddToMapCache(Handle<Context> context,
                                  Handle<FixedArray> keys,
                                  Handle<Map> map);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_FACTORY_H_