Debugger: consider try-finally scopes not catching wrt debug events.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index bdc3210ca2b0424c405862a45e06f64923db4196..3d00c514165ef97b91147b40f0e79b65882490c6 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -747,7 +747,13 @@ class Isolate {
   // clause will consume or re-throw an exception. We conservatively assume any
   // finally clause will behave as if the exception were consumed.
   enum CatchType { NOT_CAUGHT, CAUGHT_BY_JAVASCRIPT, CAUGHT_BY_EXTERNAL };
-  CatchType PredictExceptionCatcher();
+  // With the PRECISE mode, try-finally is considered to catch the exception,
+  // as the exception may or may not be rethrown. With the CONSERVATIVE mode,
+  // try-finally is considered to always rethrow. This is to meet the
+  // expectation of the debugger.
+  enum ExceptionPredictionMode { PRECISE_PREDICTION, CONSERVATIVE_PREDICTION };
+  CatchType PredictExceptionCatcher(
+      ExceptionPredictionMode prediction_mode = PRECISE_PREDICTION);

[Michael Starzinger, 2015/05/29 09:00:55]

As discussed offline: The only reason PredictExceptionCatcher exists, is for the
debugger. So if the debugger is only ever interested in the
CONSERVATIVE_PREDICTION, then we could just make that the default and drop the
PRECISE_PREDICTION altogether. WDYT?

 
   void ScheduleThrow(Object* exception);
   // Re-set pending message, script and positions reported to the TryCatch