Reland "Make v8::TryCatch able to consume natively thrown exceptions."

src/api.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/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 1833 matching lines @@
       // for reuse.  capture_message_ needs to be disabled so that DoThrow()
       // does not create a new message.
       isolate_->thread_local_top()->rethrowing_message_ = true;
       isolate_->RestorePendingMessageFromTryCatch(this);
     }
     isolate_->UnregisterTryCatchHandler(this);
     v8::internal::SimulatorStack::UnregisterCTryCatch();
     reinterpret_cast<Isolate*>(isolate_)->ThrowException(exc);
     ASSERT(!isolate_->thread_local_top()->rethrowing_message_);
   } else {
+    if (HasCaught() && isolate_->has_scheduled_exception()) {
+      // If an exception was caught but is still scheduled because no API call
+      // promoted it, then it is canceled to prevent it from being propagated.
+      // Note that this will not cancel termination exceptions.
+      isolate_->CancelScheduledExceptionFromTryCatch(this);
+    }
     isolate_->UnregisterTryCatchHandler(this);
     v8::internal::SimulatorStack::UnregisterCTryCatch();
   }
 }
 
 
 bool v8::TryCatch::HasCaught() const {
   return !reinterpret_cast<i::Object*>(exception_)->IsTheHole();
 }
 
@@ skipping 5733 matching lines @@
   Isolate* isolate = reinterpret_cast<Isolate*>(info.GetIsolate());
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 } }  // namespace v8::internal