Change exception type to Object.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index c7eb173981c0e2d7e986d456754be9633a883875..20d148e2850e1dc82abc55326967271a15482d35 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -264,21 +264,11 @@ void Isolate::IterateThread(ThreadVisitor* v, char* t) {
 
 void Isolate::Iterate(ObjectVisitor* v, ThreadLocalTop* thread) {
   // Visit the roots from the top for a given thread.
-  Object* pending;
-  // The pending exception can sometimes be a failure.  We can't show
-  // that to the GC, which only understands objects.
-  if (thread->pending_exception_->ToObject(&pending)) {
-    v->VisitPointer(&pending);
-    thread->pending_exception_ = pending;  // In case GC updated it.
-  }
+  v->VisitPointer(&thread->pending_exception_);
   v->VisitPointer(&(thread->pending_message_obj_));
   v->VisitPointer(BitCast<Object**>(&(thread->pending_message_script_)));
   v->VisitPointer(BitCast<Object**>(&(thread->context_)));
-  Object* scheduled;
-  if (thread->scheduled_exception_->ToObject(&scheduled)) {
-    v->VisitPointer(&scheduled);
-    thread->scheduled_exception_ = scheduled;
-  }
+  v->VisitPointer(&thread->scheduled_exception_);
 
   for (v8::TryCatch* block = thread->TryCatchHandler();
        block != NULL;
@@ -912,7 +902,7 @@ Failure* Isolate::Throw(Object* exception, MessageLocation* location) {
 }
 
 
-Failure* Isolate::ReThrow(MaybeObject* exception) {
+Failure* Isolate::ReThrow(Object* exception) {
   bool can_be_caught_externally = false;
   bool catchable_by_javascript = is_catchable_by_javascript(exception);
   ShouldReportException(&can_be_caught_externally, catchable_by_javascript);
@@ -969,7 +959,7 @@ void Isolate::RestorePendingMessageFromTryCatch(v8::TryCatch* handler) {
 
 
 Failure* Isolate::PromoteScheduledException() {
-  MaybeObject* thrown = scheduled_exception();
+  Object* thrown = scheduled_exception();
   clear_scheduled_exception();
   // Re-throw the exception to avoid getting repeated error reporting.
   return ReThrow(thrown);
@@ -1813,9 +1803,6 @@ void Isolate::PropagatePendingExceptionToExternalTryCatch() {
     try_catch_handler()->exception_ = heap()->null_value();
   } else {
     v8::TryCatch* handler = try_catch_handler();
-    // At this point all non-object (failure) exceptions have
-    // been dealt with so this shouldn't fail.
-    ASSERT(!pending_exception()->IsFailure());
     ASSERT(thread_local_top_.pending_message_obj_->IsJSMessageObject() ||
            thread_local_top_.pending_message_obj_->IsTheHole());
     ASSERT(thread_local_top_.pending_message_script_->IsScript() ||