Allow uncaught exception messaging in Object.observe callbacks.

src/runtime/runtime-observe.cc

Index: src/runtime/runtime-observe.cc
diff --git a/src/runtime/runtime-observe.cc b/src/runtime/runtime-observe.cc
index ab7f2503b18655dcc2958248330e17aad10eae61..4579136d9aa8efd1ad5b3f47d5d6e6189d8df674 100644
--- a/src/runtime/runtime-observe.cc
+++ b/src/runtime/runtime-observe.cc
@@ -52,6 +52,28 @@ RUNTIME_FUNCTION(Runtime_RunMicrotasks) {
 }
 
 
+RUNTIME_FUNCTION(Runtime_DeliverObservationChangeRecords) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 2);
+  CONVERT_ARG_HANDLE_CHECKED(JSFunction, callback, 0);
+  CONVERT_ARG_HANDLE_CHECKED(Object, argument, 1);
+  v8::TryCatch catcher;
+  // We should send a message on uncaught exception thrown during
+  // Object.observe delivery while not interrupting further delivery, thus
+  // we make a call inside a verbose TryCatch.
+  catcher.SetVerbose(true);
+  Handle<Object> argv[] = {argument};
+  USE(Execution::Call(isolate, callback, isolate->factory()->undefined_value(),
+                      arraysize(argv), argv));
+  if (isolate->has_pending_exception()) {
+    isolate->ReportPendingMessages();
+    isolate->clear_pending_exception();
+    isolate->set_external_caught_exception(false);
+  }
+  return isolate->heap()->undefined_value();
+}
+
+
 RUNTIME_FUNCTION(Runtime_GetObservationState) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 0);