Revert of [api] Clean up scopes and precheck instantiations cache

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/isolate.h"
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
@@ skipping 3237 matching lines @@
   StackGuard* stack_guard = isolate_->stack_guard();
 #ifdef USE_SIMULATOR
   // The simulator uses a separate JS stack.
   Address jssp_address = Simulator::current(isolate_)->get_sp();
   uintptr_t jssp = reinterpret_cast<uintptr_t>(jssp_address);
   if (jssp - gap < stack_guard->real_jslimit()) return true;
 #endif  // USE_SIMULATOR
   return GetCurrentStackPosition() - gap < stack_guard->real_climit();
 }
 
+SaveContext::SaveContext(Isolate* isolate)
+    : isolate_(isolate), prev_(isolate->save_context()) {
+  if (isolate->context() != NULL) {
+    context_ = Handle<Context>(isolate->context());
+  }
+  isolate->set_save_context(this);
+
+  c_entry_fp_ = isolate->c_entry_fp(isolate->thread_local_top());
+}
+
+SaveContext::~SaveContext() {
+  isolate_->set_context(context_.is_null() ? NULL : *context_);
+  isolate_->set_save_context(prev_);
+}
+
 #ifdef DEBUG
 AssertNoContextChange::AssertNoContextChange(Isolate* isolate)
     : isolate_(isolate), context_(isolate->context(), isolate) {}
 #endif  // DEBUG
 
 
 bool PostponeInterruptsScope::Intercept(StackGuard::InterruptFlag flag) {
   // First check whether the previous scope intercepts.
   if (prev_ && prev_->Intercept(flag)) return true;
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8