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

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
===================================================================
--- runtime/vm/dart_api_impl.cc	(revision 32732)
+++ runtime/vm/dart_api_impl.cc	(working copy)
@@ -4175,8 +4175,8 @@
                          " snapshot.", CURRENT_FUNC);
   }
   if (snapshot->length() != buffer_len) {
-    return Api::NewError("%s: 'buffer_len' of %" Pd " is not equal to %d which"
-                         " is the expected length in the snapshot.",
+    return Api::NewError("%s: 'buffer_len' of %" Pd " is not equal to %" Pd64
+                         " which is the expected length in the snapshot.",
                          CURRENT_FUNC, buffer_len, snapshot->length());
   }
   Library& library =