Work in progress: allow pause-on-exceptions to work in Object.observe callbacks

src/debug.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/v8.h"
 
 #include "src/api.h"
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 2540 matching lines @@
     Handle<JSObject> jspromise = Handle<JSObject>::cast(promise);
     // Mark the promise as already having triggered a message.
     Handle<Symbol> key = isolate_->factory()->promise_debug_marker_symbol();
     JSObject::SetProperty(jspromise, key, key, STRICT).Assert();
     // Check whether the promise reject is considered an uncaught exception.
     Handle<Object> has_reject_handler;
     ASSIGN_RETURN_ON_EXCEPTION_VALUE(
         isolate_, has_reject_handler,
         PromiseHasUserDefinedRejectHandler(jspromise), /* void */);
     uncaught = has_reject_handler->IsFalse();
+  } else if (!uncaught && promise->IsNull()) {
+    uncaught = true;
   }
   // Bail out if exception breaks are not active
   if (uncaught) {
     // Uncaught exceptions are reported by either flags.
     if (!(break_on_uncaught_exception_ || break_on_exception_)) return;
   } else {
     // Caught exceptions are reported is activated.
     if (!break_on_exception_) return;
   }
 
@@ skipping 831 matching lines @@
   logger_->DebugEvent("Put", message.text());
 }
 
 
 void LockingCommandMessageQueue::Clear() {
   base::LockGuard<base::Mutex> lock_guard(&mutex_);
   queue_.Clear();
 }
 
 } }  // namespace v8::internal