Implement growth policy for old space using time and space signals.

runtime/vm/heap.cc

Index: runtime/vm/heap.cc
diff --git a/runtime/vm/heap.cc b/runtime/vm/heap.cc
index 1a4df3c328eb4f54527af2524f8d398937bea608..0b2ea80c2eff93382b996fb09d923f2f2a47e668 100644
--- a/runtime/vm/heap.cc
+++ b/runtime/vm/heap.cc
@@ -77,7 +77,6 @@ uword Heap::AllocateOld(intptr_t size) {
     }
     addr = old_space_->TryAllocate(size);
     if (addr == 0) {
-      // TODO(cshapiro): Support possible heap growth and OOM exception.
       OS::PrintErr("Exhausted heap space, trying to allocate %d bytes.\n",
                    size);
     }
@@ -143,6 +142,9 @@ void Heap::CollectGarbage(Space space, ApiCallbacks api_callbacks) {
   switch (space) {
     case kNew:
       new_space_->Scavenge(invoke_api_callbacks);
+      if (new_space_->HadPromotionFailure()) {
+        old_space_->MarkSweep(true);
+      }
       break;
     case kOld:
       old_space_->MarkSweep(invoke_api_callbacks);
@@ -176,6 +178,11 @@ void Heap::CollectAllGarbage() {
 }
 
 
+void Heap::EnableGrowthControl() {
+  old_space_->EnableGrowthControl();
+}
+
+
 uword Heap::TopAddress() {
   return reinterpret_cast<uword>(new_space_->TopAddress());
 }