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

src/mips64/full-codegen-mips64.cc

Index: src/mips64/full-codegen-mips64.cc
diff --git a/src/mips64/full-codegen-mips64.cc b/src/mips64/full-codegen-mips64.cc
index 99777e0845871c696e89a47bb6b3ad7fe3446157..e46760bd17134d93dca51b836cdac7474da50847 100644
--- a/src/mips64/full-codegen-mips64.cc
+++ b/src/mips64/full-codegen-mips64.cc
@@ -2641,6 +2641,16 @@ void FullCodeGenerator::EmitClassDefineProperties(ClassLiteral* lit,
 
   // constructor
   __ CallRuntime(Runtime::kToFastProperties, 1);
+
+  if (is_strong(language_mode())) {
+    __ ld(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);
+  }
 }