Optimize ToString and NonStringToString.

Moves some uncommon type checking from ToString and
NonStringToString into DefaultString. This should
speed up string operations.

LOG=N
BUG=none

Review URL: https://codereview.chromium.org/1256323004

Cr-Commit-Position: refs/heads/master@{#29913}

src/messages.h

@@ -240,8 +240,6 @@ class CallSite {
   T(StrongSetProto,                                                            \
     "On strong object %, redefining the internal prototype is deprecated")     \
   T(SymbolKeyFor, "% is not a symbol")                                         \
-  T(SymbolToPrimitive,                                                         \
-    "Cannot convert a Symbol wrapper object to a primitive value")             \
   T(SymbolToNumber, "Cannot convert a Symbol value to a number")               \
   T(SymbolToString, "Cannot convert a Symbol value to a string")               \
   T(SimdToNumber, "Cannot convert a SIMD value to a number")                   \

src/runtime.js

@@ -766,7 +766,6 @@ function ToPrimitive(x, hint) {
   if (IS_STRING(x)) return x;
   // Normal behavior.
   if (!IS_SPEC_OBJECT(x)) return x;
-  if (IS_SYMBOL_WRAPPER(x)) throw MakeTypeError(kSymbolToPrimitive);
   if (IS_FLOAT32X4(x)) return x;
   if (hint == NO_HINT) hint = (IS_DATE(x)) ? STRING_HINT : NUMBER_HINT;
   return (hint == NUMBER_HINT) ? DefaultNumber(x) : DefaultString(x);
@@ -814,7 +813,7 @@ function ToString(x) {
   if (IS_NUMBER(x)) return %_NumberToString(x);
   if (IS_BOOLEAN(x)) return x ? 'true' : 'false';
   if (IS_UNDEFINED(x)) return 'undefined';
-  if (IS_SYMBOL(x)) throw MakeTypeError(kSymbolToString);
+  // Types that can't be converted to string are caught in DefaultString.
   return (IS_NULL(x)) ? 'null' : ToString(DefaultString(x));
 }
 
@@ -822,7 +821,7 @@ function NonStringToString(x) {
   if (IS_NUMBER(x)) return %_NumberToString(x);
   if (IS_BOOLEAN(x)) return x ? 'true' : 'false';
   if (IS_UNDEFINED(x)) return 'undefined';
-  if (IS_SYMBOL(x)) throw MakeTypeError(kSymbolToString);
+  // Types that can't be converted to string are caught in DefaultString.
   return (IS_NULL(x)) ? 'null' : ToString(DefaultString(x));
 }
 
@@ -960,6 +959,7 @@ function DefaultNumber(x) {
 // ECMA-262, section 8.6.2.6, page 28.
 function DefaultString(x) {
   if (!IS_SYMBOL_WRAPPER(x)) {
+    if (IS_SYMBOL(x)) throw MakeTypeError(kSymbolToString);
     var toString = x.toString;
     if (IS_SPEC_FUNCTION(toString)) {
       var s = %_CallFunction(x, toString);

test/mjsunit/messages.js

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --stack-size=100 --harmony --harmony-reflect --harmony-arrays
-// Flags: --harmony-regexps --harmony-simd --strong-mode
+// Flags: --stack-size=100 --harmony --harmony-reflect --harmony-regexps
+// Flags: --harmony-simd --strong-mode
 
 function test(f, expected, type) {
   try {
@@ -308,11 +308,6 @@ test(function() {
   "a" + 1;
 }, "In strong mode, implicit conversions are deprecated", TypeError);
 
-// kSymbolToPrimitive
-test(function() {
-  1 + Object(Symbol());
-}, "Cannot convert a Symbol wrapper object to a primitive value", TypeError);
-
 // kSymbolToString
 test(function() {
   "" + Symbol();