Output max incremental step delay in trace_gc_nvp.

R=mstarzinger@chromium.org

Review URL: https://chromiumcodereview.appspot.com/11377134

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12959 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap.cc

@@ -7227,6 +7227,7 @@ GCTracer::~GCTracer() {
     } else {
       PrintF("stepscount=%d ", steps_count_);
       PrintF("stepstook=%d ", static_cast<int>(steps_took_));
+      PrintF("longeststep=%.f ", longest_step_);
     }
 
     PrintF("\n");