chakrashim: let caller TryCatch record exception

It's possible a caller uses TryCatch, call an external function which
throws an exception, then continue to make other calls to script engine.
The exception is supposed to be caught by the TryCatch.

Fixes `test-async-wrap-throw-from-callback` on node-chakracore.

PR-URL: #54
Reviewed-By: Sandeep Agarwal <Agarwal.Sandeep@microsoft.com>

deps/chakrashim/include/v8.h

@@ -2350,12 +2350,14 @@ class V8_EXPORT TryCatch {
  private:
   friend class Function;
 
+  void SetNonUser() { user = false; }
   void GetAndClearException();
   void CheckReportExternalException();
 
   JsValueRef error;
   TryCatch* prev;
   bool rethrow;
+  bool user;
   bool verbose;
 };
 

deps/chakrashim/src/v8function.cc

@@ -69,6 +69,7 @@ MaybeLocal<Value> Function::Call(Local<Context> context,
   JsValueRef result;
   {
     TryCatch tryCatch;
+    tryCatch.SetNonUser();
     if (JsCallFunction((JsValueRef)this, args, argc + 1,
                        &result) != JsNoError) {
       tryCatch.CheckReportExternalException();

deps/chakrashim/src/v8trycatch.cc

@@ -26,6 +26,7 @@ namespace v8 {
 TryCatch::TryCatch(Isolate* isolate)
     : error(JS_INVALID_REFERENCE),
       rethrow(false),
+      user(true),
       verbose(false) {
   jsrt::IsolateShim * isolateShim = jsrt::IsolateShim::GetCurrent();
   prev = isolateShim->tryCatchStackTop;
@@ -156,13 +157,20 @@ void TryCatch::SetVerbose(bool value) {
 }
 
 void TryCatch::CheckReportExternalException() {
+  // Let caller TryCatch record the exception
+  TryCatch* tryCatch = (prev != nullptr && prev->user) ? prev : this;
+  if (tryCatch == prev) {
+    tryCatch->GetAndClearException();
+  }
+
   // This is only used by Function::Call. If caller does not use TryCatch to
   // handle external exceptions, or uses a TryCatch and SetVerbose(),
   // we'll report the external exception message (triggers uncaughtException).
   if (prev == nullptr || prev->verbose) {
-    jsrt::IsolateShim::GetCurrent()->ForEachMessageListener([this](
-        void * messageListener) {
-      ((v8::MessageCallback)messageListener)(Message(), Exception());
+    jsrt::IsolateShim::GetCurrent()->ForEachMessageListener(
+      [tryCatch](void * messageListener) {
+        ((v8::MessageCallback)messageListener)(tryCatch->Message(),
+                                               tryCatch->Exception());
     });
   } else {
     rethrow = true;  // Otherwise leave the exception as is