Bug 1611855 - Worklet must be part of the same parent's agentCluster - part 3 - update the scope after a writing, r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D61183

--HG--
extra : moz-landing-system : lando

dom/base/StructuredCloneHolder.cpp

@@ -193,6 +193,10 @@ bool StructuredCloneHolderBase::Write(
     return false;
   }
 
+  // Let's update our scope to the final one. The new one could be more
+  // restrictive of the current one.
+  MOZ_ASSERT(mStructuredCloneScope >= mBuffer->scope());
+  mStructuredCloneScope = mBuffer->scope();
   return true;
 }
 

js/public/StructuredClone.h

@@ -552,6 +552,11 @@ class MOZ_NON_MEMMOVABLE JS_PUBLIC_API JSStructuredCloneData {
   }
 
   void discardTransferables();
+
+ private:
+  // This internal method exposes the real value of scope_. It's meant to be
+  // used only when starting the writing.
+  JS::StructuredCloneScope scopeForInternalWriting() const { return scope_; }
 };
 
 /**

js/src/vm/StructuredClone.cpp

@@ -3211,9 +3211,9 @@ bool JSAutoStructuredCloneBuffer::write(
     const JS::CloneDataPolicy& cloneDataPolicy,
     const JSStructuredCloneCallbacks* optionalCallbacks, void* closure) {
   clear();
-  bool ok =
+  bool ok = JS_WriteStructuredClone(
-      JS_WriteStructuredClone(cx, value, &data_, data_.scope(), cloneDataPolicy,
+      cx, value, &data_, data_.scopeForInternalWriting(), cloneDataPolicy,
-                              optionalCallbacks, closure, transferable);
+      optionalCallbacks, closure, transferable);
 
   if (ok) {
     data_.ownTransferables_ = OwnTransferablePolicy::OwnsTransferablesIfAny;