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

src/arm64/full-codegen-arm64.cc

Index: src/arm64/full-codegen-arm64.cc
diff --git a/src/arm64/full-codegen-arm64.cc b/src/arm64/full-codegen-arm64.cc
index 09e08f3428d0619ceb95fd02b14e996f7a0c4a1d..500b594a726e4e16ad31bd6ac88700716c655520 100644
--- a/src/arm64/full-codegen-arm64.cc
+++ b/src/arm64/full-codegen-arm64.cc
@@ -2352,6 +2352,17 @@ void FullCodeGenerator::EmitClassDefineProperties(ClassLiteral* lit,
 
   // constructor
   __ CallRuntime(Runtime::kToFastProperties, 1);
+
+  if (is_strong(language_mode())) {
+    __ Ldr(scratch,
+           FieldMemOperand(x0, JSFunction::kPrototypeOrInitialMapOffset));
+    __ push(x0);
+    __ Push(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);
+  }
 }