ES6 symbols: turn symbols into a proper primitive type

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 205781b9d9f51da066e0a06ca9ca7fa52ab6d94a..588b6b6d7b535679464b627e1b441b58566cc191 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -2116,6 +2116,12 @@ void LCodeGen::DoBranch(LBranch* instr) {
         __ bind(&not_string);
       }
 
+      if (expected.Contains(ToBooleanStub::SYMBOL)) {
+        // Symbol value -> true.
+        __ CmpInstanceType(map, SYMBOL_TYPE);
+        __ j(equal, true_label);
+      }
+
       if (expected.Contains(ToBooleanStub::HEAP_NUMBER)) {
         // heap number -> false iff +0, -0, or NaN.
         Label not_heap_number;
@@ -5979,6 +5985,11 @@ Condition LCodeGen::EmitTypeofIs(Label* true_label,
               1 << Map::kIsUndetectable);
     final_branch_condition = zero;
 
+  } else if (type_name->Equals(heap()->symbol_string())) {
+    __ JumpIfSmi(input, false_label);
+    __ CmpObjectType(input, SYMBOL_TYPE, input);
+    final_branch_condition = equal;
+
   } else if (type_name->Equals(heap()->boolean_string())) {
     __ cmp(input, factory()->true_value());
     __ j(equal, true_label);
@@ -6013,13 +6024,7 @@ Condition LCodeGen::EmitTypeofIs(Label* true_label,
       __ cmp(input, factory()->null_value());
       __ j(equal, true_label);
     }
-    if (FLAG_harmony_symbols) {
-      __ CmpObjectType(input, SYMBOL_TYPE, input);
-      __ j(equal, true_label);
-      __ CmpInstanceType(input, FIRST_NONCALLABLE_SPEC_OBJECT_TYPE);
-    } else {
-      __ CmpObjectType(input, FIRST_NONCALLABLE_SPEC_OBJECT_TYPE, input);
-    }
+    __ CmpObjectType(input, FIRST_NONCALLABLE_SPEC_OBJECT_TYPE, input);
     __ j(below, false_label);
     __ CmpInstanceType(input, LAST_NONCALLABLE_SPEC_OBJECT_TYPE);
     __ j(above, false_label);