Make fatal out of memory messages uniform.

runtime/vm/clustered_snapshot.cc

Index: runtime/vm/clustered_snapshot.cc
diff --git a/runtime/vm/clustered_snapshot.cc b/runtime/vm/clustered_snapshot.cc
index d9e65ad479666f2d11549b0fe08dc149498abdc5..afda5be4ae719498937467327558ba6955f0fb4d 100644
--- a/runtime/vm/clustered_snapshot.cc
+++ b/runtime/vm/clustered_snapshot.cc
@@ -28,7 +28,7 @@ static RawObject* AllocateUninitialized(PageSpace* old_space, intptr_t size) {
   uword address = old_space->TryAllocateDataBumpLocked(size,
                                                        PageSpace::kForceGrowth);
   if (address == 0) {
-    FATAL("Out of memory");
+    OUT_OF_MEMORY();
   }
   return reinterpret_cast<RawObject*>(address + kHeapObjectTag);
 }