[Bindings] Create and use V8 context snapshots

pdf/pdfium/pdfium_engine.cc

Index: pdf/pdfium/pdfium_engine.cc
diff --git a/pdf/pdfium/pdfium_engine.cc b/pdf/pdfium/pdfium_engine.cc
index 8ab5a1bb67b2f5d879aeaf7561377195c36ad1c2..0f9460d91af063ee7eb8b18caa3244f2690496b8 100644
--- a/pdf/pdfium/pdfium_engine.cc
+++ b/pdf/pdfium/pdfium_engine.cc
@@ -594,8 +594,8 @@ void SetUpV8() {
   gin::IsolateHolder::Initialize(gin::IsolateHolder::kNonStrictMode,
                                  gin::IsolateHolder::kStableV8Extras,
                                  gin::ArrayBufferAllocator::SharedInstance());
-  g_isolate_holder = new gin::IsolateHolder(base::ThreadTaskRunnerHandle::Get(),
-                                            gin::IsolateHolder::kSingleThread);
+  g_isolate_holder =
+      new gin::IsolateHolder(base::ThreadTaskRunnerHandle::Get());
   g_isolate_holder->isolate()->Enter();
 }