Use v8::Local<> in DynPropGetterAdapter()

This CL avoids using v8::Global in DynPropGetterAdapter() by returning
a v8::Local<v8::Value> instead.

- Used v8::EscapableHandleScope to safely return the local value created
  within the function across the handle scope.

Bug: 42270615
Change-Id: Ib3a4f52e009ee946c757db666d8cb263a9087bd6
TAG=agy
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/148092
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

fxjs/xfa/cfxjse_class.cpp

diff --git a/fxjs/xfa/cfxjse_class.cpp b/fxjs/xfa/cfxjse_class.cpp
index 6b76887..5fde4e4 100644
--- a/fxjs/xfa/cfxjse_class.cpp
+++ b/fxjs/xfa/cfxjse_class.cpp
@@ -138,7 +138,7 @@
   }
 }
 
-v8::Global<v8::Value> DynPropGetterAdapter(
+v8::Local<v8::Value> DynPropGetterAdapter(
     v8::Isolate* pIsolate,
     const FXJSE_CLASS_DESCRIPTOR* pClassDescriptor,
     v8::Local<v8::Object> pObject,
@@ -150,13 +150,11 @@
           : FXJSE_ClassPropType::kProperty;
   if (nPropType == FXJSE_ClassPropType::kProperty) {
     if (pClassDescriptor->dynPropGetter) {
-      return v8::Global<v8::Value>(
-          pIsolate,
-          pClassDescriptor->dynPropGetter(pIsolate, pObject, szPropName));
+      return pClassDescriptor->dynPropGetter(pIsolate, pObject, szPropName);
     }
   } else if (nPropType == FXJSE_ClassPropType::kMethod) {
     if (pClassDescriptor->dynMethodCall) {
-      v8::HandleScope hscope(pIsolate);
+      v8::EscapableHandleScope hscope(pIsolate);
       v8::Local<v8::ObjectTemplate> hCallBackInfoTemplate =
           v8::ObjectTemplate::New(pIsolate);
       hCallBackInfoTemplate->SetInternalFieldCount(2);
@@ -168,15 +166,14 @@
           kDefaultPDFiumTag);
       hCallBackInfo->SetInternalField(
           1, fxv8::NewStringHelper(pIsolate, szPropName));
-      return v8::Global<v8::Value>(
-          pIsolate,
+      return hscope.Escape(
           v8::Function::New(pIsolate->GetCurrentContext(),
                             DynPropGetterAdapter_MethodCallback, hCallBackInfo,
                             0, v8::ConstructorBehavior::kThrow)
               .ToLocalChecked());
     }
   }
-  return v8::Global<v8::Value>();
+  return v8::Local<v8::Value>();
 }
 
 void DynPropSetterAdapter(v8::Isolate* pIsolate,
@@ -246,10 +243,9 @@
   // SAFETY: required from V8.
   auto szFxPropName =
       UNSAFE_BUFFERS(ByteStringView(*szPropName, szPropName.length()));
-  v8::Global<v8::Value> new_value = DynPropGetterAdapter(
+  v8::Local<v8::Value> new_value = DynPropGetterAdapter(
       info.GetIsolate(), pClass, info.HolderV2(), szFxPropName);
-  info.GetReturnValue().Set(
-      v8::Local<v8::Value>::New(info.GetIsolate(), new_value));
+  info.GetReturnValue().Set(new_value);
   return v8::Intercepted::kYes;
 }