Track live instance and allocation counts for classes

runtime/vm/pages.cc

Index: runtime/vm/pages.cc
diff --git a/runtime/vm/pages.cc b/runtime/vm/pages.cc
index 06f15b31e3c6951d9f4ea5532f14ce8aa61cced1..b30c9a2e6a36676a16ca8ef850df2a6541879ea0 100644
--- a/runtime/vm/pages.cc
+++ b/runtime/vm/pages.cc
@@ -131,7 +131,9 @@ PageSpace::PageSpace(Heap* heap, intptr_t max_capacity_in_words)
       sweeping_(false),
       page_space_controller_(FLAG_heap_growth_space_ratio,
                              FLAG_heap_growth_rate,
-                             FLAG_heap_growth_time_ratio) {
+                             FLAG_heap_growth_time_ratio),
+      gc_time_micros_(0),
+      collections_(0) {
 }