VM: Make Dart::FeaturesString respect isolate flags controlling asserts and type checks.

runtime/vm/snapshot.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef RUNTIME_VM_SNAPSHOT_H_
 #define RUNTIME_VM_SNAPSHOT_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/bitfield.h"
@@ skipping 378 matching lines @@
                   DeserializeState state,
                   bool defer_canonicalization = false);
 
   // Get an object from the backward references list.
   Object* GetBackRef(intptr_t id);
 
   // Read a script snapshot.
   RawObject* ReadScriptSnapshot();
 
   // Read version number of snapshot and verify.
-  RawApiError* VerifyVersionAndFeatures();
+  RawApiError* VerifyVersionAndFeatures(Isolate* isolate);
 
   RawObject* NewInteger(int64_t value);
 
  protected:
   SnapshotReader(const uint8_t* buffer,
                  intptr_t size,
                  Snapshot::Kind kind,
                  ZoneGrowableArray<BackRefNode>* backward_references,
                  Thread* thread);
   ~SnapshotReader() {}
@@ skipping 601 matching lines @@
  private:
   SnapshotWriter* writer_;
   bool as_references_;
 
   DISALLOW_COPY_AND_ASSIGN(SnapshotWriterVisitor);
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_SNAPSHOT_H_