Don't allow statement-nodes in expression contexts.

lib/compiler/implementation/ssa/optimize.dart

 // 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.
 
 interface OptimizationPhase {
   String get name();
   void visitGraph(HGraph graph);
 }
 
 class SsaOptimizerTask extends CompilerTask {
@@ skipping 52 matching lines @@
       runPhases(graph, phases);
       return !work.guards.isEmpty();
     });
   }
 
   void prepareForSpeculativeOptimizations(WorkItem work, HGraph graph) {
     measure(() {
       // In order to generate correct code for the bailout version, we did not
       // propagate types from the instruction to the type guard. We do it
       // now to be able to optimize further.
-      work.guards.forEach((HTypeGuard guard) { guard.isOn = true; });
+      work.guards.forEach((HTypeGuard guard) { guard.isEnabled = true; });
       // We also need to insert range and integer checks for the type
       // guards. Now that they claim to have a certain type, some
       // depending instructions might become builtin (like native array
       // accesses) and need to be checked.
       // Also run the type propagator, to please the codegen in case
       // no other optimization is run.
       runPhases(graph,
         <OptimizationPhase>[new SsaCheckInserter(backend),
                             new SsaTypePropagator(compiler)]);
     });
@@ skipping 1188 matching lines @@
             break;
           default:
             assert(false);
             break;
         }
       }
     }
   }
 
 }