Improve --trace-gc-verbose to show sum of all spaces.

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index 0515019630ad1d7e69f0f3b788072b50b090681c..210530199f82c488431ed03b6fc7b42fce4b61ee 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -371,6 +371,12 @@ void Heap::PrintShortHeapStatistics() {
            lo_space_->SizeOfObjects() / KB,
            lo_space_->Available() / KB,
            lo_space_->CommittedMemory() / KB);
+  PrintPID("All spaces,         used: %6" V8_PTR_PREFIX "d KB"
+               ", available: %6" V8_PTR_PREFIX "d KB"
+               ", committed: %6" V8_PTR_PREFIX "d KB\n",
+           this->SizeOfObjects() / KB,
+           this->Available() / KB,
+           this->CommittedMemory() / KB);
   PrintPID("Total time spent in GC  : %d ms\n", total_gc_time_ms_);
 }