Introduce new runtime function to make join with lower memory usage.

src/runtime.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 110 matching lines @@
   F(NumberAdd, 2, 1) \
   F(NumberSub, 2, 1) \
   F(NumberMul, 2, 1) \
   F(NumberDiv, 2, 1) \
   F(NumberMod, 2, 1) \
   F(NumberUnaryMinus, 1, 1) \
   F(NumberAlloc, 0, 1) \
   \
   F(StringAdd, 2, 1) \
   F(StringBuilderConcat, 3, 1) \
+  F(StringBuilderJoin, 3, 1) \
   \
   /* Bit operations */ \
   F(NumberOr, 2, 1) \
   F(NumberAnd, 2, 1) \
   F(NumberXor, 2, 1) \
   F(NumberNot, 1, 1) \
   \
   F(NumberShl, 2, 1) \
   F(NumberShr, 2, 1) \
   F(NumberSar, 2, 1) \
@@ skipping 416 matching lines @@
                                                 int position);
 
   // Helper functions used stubs.
   static void PerformGC(Object* result);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_RUNTIME_H_