Revert "Move precompilation-related flags to flags list."

runtime/vm/snapshot.cc

 // 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.
 
 #include "vm/snapshot.h"
 
 #include "platform/assert.h"
 #include "vm/bootstrap.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart.h"
@@ skipping 10 matching lines @@
 #include "vm/verified_memory.h"
 #include "vm/version.h"
 
 // We currently only expect the Dart mutator to read snapshots.
 #define ASSERT_NO_SAFEPOINT_SCOPE()                            \
     isolate()->AssertCurrentThreadIsMutator();                 \
     ASSERT(thread()->no_safepoint_scope_depth() != 0)
 
 namespace dart {
 
+DECLARE_FLAG(bool, use_field_guards);
+
+
 static const int kNumVmIsolateSnapshotReferences = 32 * KB;
 static const int kNumInitialReferencesInFullSnapshot = 160 * KB;
 static const int kNumInitialReferences = 64;
 
 
 static bool IsSingletonClassId(intptr_t class_id) {
   // Check if this is a singleton object class which is shared by all isolates.
   return ((class_id >= kClassCid && class_id <= kUnwindErrorCid) ||
           (class_id >= kNullCid && class_id <= kVoidCid));
 }
@@ skipping 2634 matching lines @@
   if (setjmp(*jump.Set()) == 0) {
     NoSafepointScope no_safepoint;
     WriteObject(obj.raw());
   } else {
     ThrowException(exception_type(), exception_msg());
   }
 }
 
 
 }  // namespace dart