[strong] class objects created in strong mode have their prototype frozen

src/x87/full-codegen-x87.cc

Index: src/x87/full-codegen-x87.cc
diff --git a/src/x87/full-codegen-x87.cc b/src/x87/full-codegen-x87.cc
index cc4644c04429dde0be588582d441eb59481b012f..01e42b0d28fabaeb77057d3eecec37e8451b9165 100644
--- a/src/x87/full-codegen-x87.cc
+++ b/src/x87/full-codegen-x87.cc
@@ -2554,6 +2554,19 @@ void FullCodeGenerator::EmitClassDefineProperties(ClassLiteral* lit,
 
   // constructor
   __ CallRuntime(Runtime::kToFastProperties, 1);
+
+  if (is_strong(language_mode())) {
+    __ mov(scratch,
+           FieldOperand(eax, JSFunction::kPrototypeOrInitialMapOffset));
+    __ push(eax);
+    __ push(scratch);
+    // TODO(conradw): It would be more efficient to define the properties with
+    // the right attributes the first time round.
+    // Freeze the prototype.
+    __ CallRuntime(Runtime::kObjectFreeze, 1);
+    // Freeze the constructor.
+    __ CallRuntime(Runtime::kObjectFreeze, 1);
+  }
 }