ES6 symbols: Implement Symbol intrinsic and basic functionality

src/ia32/builtins-ia32.cc

Index: src/ia32/builtins-ia32.cc
diff --git a/src/ia32/builtins-ia32.cc b/src/ia32/builtins-ia32.cc
index c689afb28a605c0b2ad346211763bef1241af308..c8653f49983c09b23cb6458284c22de0c3ab675b 100644
--- a/src/ia32/builtins-ia32.cc
+++ b/src/ia32/builtins-ia32.cc
@@ -383,6 +383,10 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
     __ CmpObjectType(eax, FIRST_SPEC_OBJECT_TYPE, ecx);
     __ j(above_equal, &exit);
 
+    // Symbols are "objects".
+    __ CmpInstanceType(ecx, SYMBOL_TYPE);
+    __ j(equal, &exit);
+
     // Throw away the result of the constructor invocation and use the
     // on-stack receiver as the result.
     __ bind(&use_receiver);