[vm, gc] Use the standard out-of-memory message when the scavenger fails to copy.

Bug: b/155227688
Change-Id: I865f4abaf82469c89739f3effeb0a4683ceb2686
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/149900
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>

runtime/vm/heap/scavenger.cc

@@ -278,7 +278,7 @@ class ScavengerVisitorBase : public ObjectPointerVisitor {
           // To-space was exhausted by fragmentation and old-space could not
           // grow.
           if (UNLIKELY(new_addr == 0)) {
-            FATAL("Failed to allocate during scavenge");
+            OUT_OF_MEMORY();
           }
         }
       }