Implement correct checking for inherited readonliness on assignment.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index e11cbdc4fd3853f23d4e79561df897807efe1cda..582eec7b9db0acf81c31461cccaabb9432a37426 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -2155,17 +2155,16 @@ class JSObject: public JSReceiver {
       bool check_prototype,
       SetPropertyMode set_mode);
 
-  // Searches the prototype chain for a callback setter and sets the property
-  // with the setter if it finds one. The '*found' flag indicates whether
-  // a setter was found or not.
-  // This function can cause GC and can return a failure result with
-  // '*found==true'.
-  MUST_USE_RESULT MaybeObject* SetPropertyWithCallbackSetterInPrototypes(
+  // Searches the prototype chain for property 'name'. If it is found and
+  // has a setter, invoke it and set '*done' to true. If it is found and is
+  // read-only, reject and set '*done' to true. Otherwise, set '*done' to
+  // false. Can cause GC and can return a failure result with '*done==true'.
+  MUST_USE_RESULT MaybeObject* SetPropertyViaPrototypes(
       String* name,
       Object* value,
       PropertyAttributes attributes,
-      bool* found,
-      StrictModeFlag strict_mode);
+      StrictModeFlag strict_mode,
+      bool* done);
 
   MUST_USE_RESULT MaybeObject* DeletePropertyPostInterceptor(String* name,
                                                              DeleteMode mode);
@@ -7728,14 +7727,17 @@ class JSProxy: public JSReceiver {
       Object* value,
       StrictModeFlag strict_mode);
 
-  // If the handler defines an accessor property, invoke its setter
-  // (or throw if only a getter exists) and set *found to true. Otherwise false.
-  MUST_USE_RESULT MaybeObject* SetPropertyWithHandlerIfDefiningSetter(
+  // If the handler defines an accessor property with a setter, invoke it.
+  // If it defines an accessor property without a setter, or a data property
+  // that is read-only, throw. In all these cases set '*done' to true,
+  // otherwise set it to false.
+  MUST_USE_RESULT MaybeObject* SetPropertyViaPrototypesWithHandler(
+      JSObject* receiver,
       String* name,
       Object* value,
       PropertyAttributes attributes,
       StrictModeFlag strict_mode,
-      bool* found);
+      bool* done);
 
   MUST_USE_RESULT MaybeObject* DeletePropertyWithHandler(
       String* name,