Provide handle scope when printing stack trace for debugging.

It would be nice for 'jst' to work even when no handle scope has been created yet.

R=cbruni@chromium.org

Review-Url: https://codereview.chromium.org/2119313002
Cr-Commit-Position: refs/heads/master@{#37541}

src/isolate.cc

@@ -823,6 +823,7 @@ static void PrintFrames(Isolate* isolate,
 void Isolate::PrintStack(StringStream* accumulator, PrintStackMode mode) {
   // The MentionedObjectCache is not GC-proof at the moment.
   DisallowHeapAllocation no_gc;
+  HandleScope scope(this);
   DCHECK(accumulator->IsMentionedObjectCacheClear(this));
 
   // Avoid printing anything if there are no frames.