Fixed a couple of failing DCHECK(has_pending_exception()).

src/runtime/runtime-debug.cc

Index: src/runtime/runtime-debug.cc
diff --git a/src/runtime/runtime-debug.cc b/src/runtime/runtime-debug.cc
index 660fc7ffa2b1055010db4f37751b3a297c8b2e26..cdafdd2271ea0f51b1b0831cc65e240adcbb2a74 100644
--- a/src/runtime/runtime-debug.cc
+++ b/src/runtime/runtime-debug.cc
@@ -2747,6 +2747,7 @@ RUNTIME_FUNCTION(Runtime_DebugGetLoadedScripts) {
   Handle<FixedArray> instances;
   {
     DebugScope debug_scope(isolate->debug());
+    if (debug_scope.failed()) return isolate->heap()->exception();
     // Fill the script objects.
     instances = isolate->debug()->GetLoadedScripts();
   }