Move symbol table from per isolate snapshot to vm isolate snapshot, this reduces the per isolate in…

runtime/vm/benchmark_test.cc

Index: runtime/vm/benchmark_test.cc
===================================================================
--- runtime/vm/benchmark_test.cc	(revision 45789)
+++ runtime/vm/benchmark_test.cc	(working copy)
@@ -541,8 +541,10 @@
     intptr_t buffer_len = writer.BytesWritten();
 
     // Read object back from the snapshot.
-    SnapshotReader reader(buffer, buffer_len, Snapshot::kMessage, isolate,
-                          zone.GetZone());
+    MessageSnapshotReader reader(buffer,
+                                 buffer_len,
+                                 isolate,
+                                 zone.GetZone());
     reader.ReadObject();
   }
   timer.Stop();
@@ -565,8 +567,10 @@
     intptr_t buffer_len = writer.BytesWritten();
 
     // Read object back from the snapshot.
-    SnapshotReader reader(buffer, buffer_len, Snapshot::kMessage, isolate,
-                          zone.GetZone());
+    MessageSnapshotReader reader(buffer,
+                                 buffer_len,
+                                 isolate,
+                                 zone.GetZone());
     reader.ReadObject();
   }
   timer.Stop();
@@ -591,8 +595,10 @@
     intptr_t buffer_len = writer.BytesWritten();
 
     // Read object back from the snapshot.
-    SnapshotReader reader(buffer, buffer_len, Snapshot::kMessage, isolate,
-                          zone.GetZone());
+    MessageSnapshotReader reader(buffer,
+                                 buffer_len,
+                                 isolate,
+                                 zone.GetZone());
     reader.ReadObject();
     free(buffer);
   }