Improve array to string conversion.

src/runtime.h

 // Copyright 2012 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 95 matching lines @@
   \
   /* Array join support */ \
   F(PushIfAbsent, 2, 1) \
   F(ArrayConcat, 1, 1) \
   \
   /* Conversions */ \
   F(ToBool, 1, 1) \
   F(Typeof, 1, 1) \
   \
   F(StringToNumber, 1, 1) \
-  F(StringFromCharCodeArray, 1, 1) \
   F(StringParseInt, 2, 1) \
   F(StringParseFloat, 1, 1) \
   F(StringToLowerCase, 1, 1) \
   F(StringToUpperCase, 1, 1) \
   F(StringSplit, 3, 1) \
   F(CharFromCode, 1, 1) \
   F(URIEscape, 1, 1) \
   F(URIUnescape, 1, 1) \
-  F(BasicJSONStringify, 1, 1) \
-  F(QuoteJSONString, 1, 1) \
-  F(QuoteJSONStringComma, 1, 1) \
-  F(QuoteJSONStringArray, 1, 1) \
   \
   F(NumberToString, 1, 1) \
   F(NumberToStringSkipCache, 1, 1) \
   F(NumberToInteger, 1, 1) \
   F(NumberToIntegerMapMinusZero, 1, 1) \
   F(NumberToJSUint32, 1, 1) \
   F(NumberToJSInt32, 1, 1) \
   F(NumberToSmi, 1, 1) \
   F(AllocateHeapNumber, 0, 1) \
   \
@@ skipping 48 matching lines @@
   \
   /* Regular expressions */ \
   F(RegExpCompile, 3, 1) \
   F(RegExpExec, 4, 1) \
   F(RegExpExecMultiple, 4, 1) \
   F(RegExpInitializeObject, 5, 1) \
   F(RegExpConstructResult, 3, 1) \
   \
   /* JSON */ \
   F(ParseJson, 1, 1) \
+  F(BasicJSONStringify, 1, 1) \
+  F(QuoteJSONString, 1, 1) \
+  F(QuoteJSONStringComma, 1, 1) \
+  F(QuoteJSONStringArray, 1, 1) \
   \
   /* Strings */ \
   F(StringCharCodeAt, 2, 1) \
   F(StringIndexOf, 3, 1) \
   F(StringLastIndexOf, 3, 1) \
   F(StringLocaleCompare, 2, 1) \
   F(SubString, 3, 1) \
   F(StringReplaceRegExpWithString, 4, 1) \
   F(StringReplaceOneCharWithString, 3, 1) \
   F(StringMatch, 3, 1) \
   F(StringTrim, 3, 1) \
   F(StringToArray, 2, 1) \
   F(NewStringWrapper, 1, 1) \
+  F(NewString, 2, 1) \
+  F(TruncateString, 2, 1) \
   \
   /* Numbers */ \
   F(NumberToRadixString, 2, 1) \
   F(NumberToFixed, 2, 1) \
   F(NumberToExponential, 2, 1) \
   F(NumberToPrecision, 2, 1)
 
 #define RUNTIME_FUNCTION_LIST_ALWAYS_2(F) \
   /* Reflection */ \
   F(FunctionSetInstanceClassName, 2, 1) \
@@ skipping 302 matching lines @@
   F(IsRegExp, 1, 1)                                                          \
   F(IsConstructCall, 0, 1)                                                   \
   F(CallFunction, -1 /* receiver + n args + function */, 1)                  \
   F(ArgumentsLength, 0, 1)                                                   \
   F(Arguments, 1, 1)                                                         \
   F(ValueOf, 1, 1)                                                           \
   F(SetValueOf, 2, 1)                                                        \
   F(DateField, 2 /* date object, field index */, 1)                          \
   F(StringCharFromCode, 1, 1)                                                \
   F(StringCharAt, 2, 1)                                                      \
+  F(OneByteSeqStringSetChar, 3, 1)                                           \
+  F(TwoByteSeqStringSetChar, 3, 1)                                           \
   F(ObjectEquals, 2, 1)                                                      \
   F(RandomHeapNumber, 0, 1)                                                  \
   F(IsObject, 1, 1)                                                          \
   F(IsFunction, 1, 1)                                                        \
   F(IsUndetectableObject, 1, 1)                                              \
   F(IsSpecObject, 1, 1)                                                      \
   F(IsStringWrapperSafeForDefaultValueOf, 1, 1)                              \
   F(MathPow, 2, 1)                                                           \
   F(MathSin, 1, 1)                                                           \
   F(MathCos, 1, 1)                                                           \
@@ skipping 176 matching lines @@
 //---------------------------------------------------------------------------
 // Constants used by interface to runtime functions.
 
 class DeclareGlobalsEvalFlag:     public BitField<bool,         0, 1> {};
 class DeclareGlobalsNativeFlag:   public BitField<bool,         1, 1> {};
 class DeclareGlobalsLanguageMode: public BitField<LanguageMode, 2, 2> {};
 
 } }  // namespace v8::internal
 
 #endif  // V8_RUNTIME_H_