Another round of cleanups for http://www.dartbug.com/15922

runtime/vm/dart.cc

Index: runtime/vm/dart.cc
===================================================================
--- runtime/vm/dart.cc	(revision 32732)
+++ runtime/vm/dart.cc	(working copy)
@@ -216,7 +216,7 @@
     const Snapshot* snapshot = Snapshot::SetupFromBuffer(snapshot_buffer);
     ASSERT(snapshot->kind() == Snapshot::kFull);
     if (FLAG_trace_isolates) {
-      OS::Print("Size of isolate snapshot = %d\n", snapshot->length());
+      OS::Print("Size of isolate snapshot = %" Pd64 "\n", snapshot->length());
     }
     SnapshotReader reader(snapshot->content(), snapshot->length(),
                           Snapshot::kFull, isolate);