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

src/mips/full-codegen-mips.cc

Index: src/mips/full-codegen-mips.cc
diff --git a/src/mips/full-codegen-mips.cc b/src/mips/full-codegen-mips.cc
index ec362afba465c81b09f16ce8313158cf4b5d417a..3d2c9dd1fb6bf74b228b210ace840f31018fc8b3 100644
--- a/src/mips/full-codegen-mips.cc
+++ b/src/mips/full-codegen-mips.cc
@@ -2643,6 +2643,16 @@ void FullCodeGenerator::EmitClassDefineProperties(ClassLiteral* lit,
 
   // constructor
   __ CallRuntime(Runtime::kToFastProperties, 1);
+
+  if (is_strong(language_mode())) {
+    __ lw(scratch,
+          FieldMemOperand(v0, JSFunction::kPrototypeOrInitialMapOffset));
+    __ Push(v0, scratch);
+    __ CallRuntime(Runtime::kObjectFreeze, 1);
+    // TODO(conradw): It would be more efficient to define the properties with
+    // the right attributes the first time round.
+    __ CallRuntime(Runtime::kObjectFreeze, 1);
+  }
 }