Allows turning on checked mode on a per-isolate basis

runtime/vm/intrinsifier.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.
 // Class for intrinsifying functions.
 
 #include "vm/assembler.h"
 #include "vm/intrinsifier.h"
 #include "vm/flags.h"
 #include "vm/object.h"
 #include "vm/symbols.h"
@@ skipping 578 matching lines @@
                            Instance::ElementSizeFor(kArrayCid),  // index scale
                            kArrayCid,
                            Isolate::kNoDeoptId,
                            builder.TokenPos()));
   builder.AddIntrinsicReturn(new Value(result));
   return true;
 }
 
 
 bool Intrinsifier::Build_GrowableArraySetIndexed(FlowGraph* flow_graph) {
-  if (FLAG_enable_type_checks) return false;
+  if (Isolate::Current()->TypeChecksEnabled()) {
+    return false;
+  }
 
   GraphEntryInstr* graph_entry = flow_graph->graph_entry();
   TargetEntryInstr* normal_entry = graph_entry->normal_entry();
   BlockBuilder builder(flow_graph, normal_entry);
 
   Definition* value = builder.AddParameter(1);
   Definition* index = builder.AddParameter(2);
   Definition* array = builder.AddParameter(3);
 
   PrepareIndexedOp(
@@ skipping 72 matching lines @@
                                   new Value(growable_array),
                                   new Value(length),
                                   kNoStoreBarrier,
                                   builder.TokenPos()));
   Definition* null_def = builder.AddNullDefinition();
   builder.AddIntrinsicReturn(new Value(null_def));
   return true;
 }
 
 }  // namespace dart