Assert that context creation doesn't throw

src/execution.h

Index: src/execution.h
diff --git a/src/execution.h b/src/execution.h
index f26ea343082b93f68d1ac088971bef15880adc7b..a250a6ce0dda35ca3567f079c0b32920fd712ef9 100644
--- a/src/execution.h
+++ b/src/execution.h
@@ -36,16 +36,17 @@ class Execution final : public AllStatic {
                                                  int argc,
                                                  Handle<Object> argv[]);
 
-  // Call a function, just like Call(), but make sure to silently catch
-  // any thrown exceptions. The return value is either the result of
-  // calling the function (if caught exception is false) or the exception
-  // that occurred (if caught exception is true).
-  // In the exception case, exception_out holds the caught exceptions, unless
-  // it is a termination exception.
+  // Call a function, just like Call(), but handle don't report exceptions
+  // externally.
+  // The return value is either the result of
+  // calling the function (if no exception occurred), or an empty handle.
+  // If an exception was raised and exception_out is non-nullptr,  holds the
+  // caught exceptions, unless it is a termination exception. Otherwise, the
+  // exception is kept pending on the isolate.

[Yang, 2017/01/17 09:54:23]

Wait... if exception_out is nullptr, TryCall behaves the same as Call?

[jochen (gone - plz use gerrit), 2017/01/17 10:24:01]

no, Call() schedules the exception, TryCall leaves it pending

tried to clarify the comment

   static MaybeHandle<Object> TryCall(Isolate* isolate, Handle<Object> callable,
                                      Handle<Object> receiver, int argc,
                                      Handle<Object> argv[],
-                                     MaybeHandle<Object>* exception_out = NULL);
+                                     MaybeHandle<Object>* exception_out);
 };