Add more safe points in compiler

runtime/vm/zone.cc

Index: runtime/vm/zone.cc
diff --git a/runtime/vm/zone.cc b/runtime/vm/zone.cc
index 8b3cdac905faf210905786168a660c3c15e65329..46288e9876ded6b7baeb66c3b640ec6956b2734d 100644
--- a/runtime/vm/zone.cc
+++ b/runtime/vm/zone.cc
@@ -77,8 +77,11 @@ Zone::Segment* Zone::Segment::New(intptr_t size, Zone::Segment* next) {
   result->next_ = next;
   result->size_ = size;
   Thread* current = Thread::Current();
+
   if (current != NULL) {
     current->IncrementMemoryUsage(size);
+    // In case the other thread is waiting to do a scavenge.
+    current->CheckForSafepoint();

[siva, 2017/03/23 18:05:01]

Why is this check needed here? We may run into issues when it is necessary to do
a new Zone inside a NoSafepointScope block.

[erikcorry, 2017/03/27 10:23:28]

Good catch.  This one was great for keeping down the wait time, but it's not
safe unless we make NoSafePointScope into a release-mode thing and check for it.
 Removed.

   } else if (ApiNativeScope::Current() != NULL) {
     // If there is no current thread, we might be inside of a native scope.
     ApiNativeScope::IncrementNativeScopeMemoryUsage(size);