[debug] Don't notify listener of exceptions internal to a desugaring.

src/isolate.h

 // 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.
 
 #ifndef V8_ISOLATE_H_
 #define V8_ISOLATE_H_
 
 #include <memory>
 #include <queue>
 #include <set>
@@ skipping 730 matching lines @@
   // reporting was handled when the exception was thrown originally.
   Object* ReThrow(Object* exception);
 
   // Find the correct handler for the current pending exception. This also
   // clears and returns the current pending exception.
   Object* UnwindAndFindHandler();
 
   // Tries to predict whether an exception will be caught. Note that this can
   // only produce an estimate, because it is undecidable whether a finally
   // clause will consume or re-throw an exception.
-  enum CatchType { NOT_CAUGHT, CAUGHT_BY_JAVASCRIPT, CAUGHT_BY_EXTERNAL };
+  enum CatchType {
+    NOT_CAUGHT,
+    CAUGHT_BY_JAVASCRIPT,
+    CAUGHT_BY_EXTERNAL,
+    CAUGHT_BY_DESUGARING
+  };
   CatchType PredictExceptionCatcher();
 
   void ScheduleThrow(Object* exception);
   // Re-set pending message, script and positions reported to the TryCatch
   // back to the TLS for re-use when rethrowing.
   void RestorePendingMessageFromTryCatch(v8::TryCatch* handler);
   // Un-schedule an exception that was caught by a TryCatch handler.
   void CancelScheduledExceptionFromTryCatch(v8::TryCatch* handler);
   void ReportPendingMessages();
   // Return pending location if any or unfilled structure.
@@ skipping 893 matching lines @@
 
   EmbeddedVector<char, 128> filename_;
   FILE* file_;
   int scope_depth_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ISOLATE_H_