Add support for debug break in Dart source.

runtime/vm/constant_propagator.cc

 // Copyright (c) 2013, 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/constant_propagator.h"
 
 #include "vm/bit_vector.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/flow_graph_compiler.h"
 #include "vm/flow_graph_range_analysis.h"
@@ skipping 164 matching lines @@
 void ConstantPropagator::VisitThrow(ThrowInstr* instr) {
   // Nothing to do.
 }
 
 
 void ConstantPropagator::VisitReThrow(ReThrowInstr* instr) {
   // Nothing to do.
 }
 
 
+void ConstantPropagator::VisitStop(StopInstr* instr) {
+  // Nothing to do.
+}
+
+
 void ConstantPropagator::VisitGoto(GotoInstr* instr) {
   SetReachable(instr->successor());
 
   // Phi value depends on the reachability of a predecessor. We have
   // to revisit phis every time a predecessor becomes reachable.
   for (PhiIterator it(instr->successor()); !it.Done(); it.Advance()) {
     it.Current()->Accept(this);
   }
 }
 
@@ skipping 1463 matching lines @@
   graph_->MergeBlocks();
   GrowableArray<BitVector*> dominance_frontier;
   graph_->ComputeDominators(&dominance_frontier);
 
   if (FLAG_trace_constant_propagation) {
     FlowGraphPrinter::PrintGraph("After CP", graph_);
   }
 }
 
 }  // namespace dart