Add support for debug break in Dart source.

runtime/vm/intermediate_language_x64.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/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 6139 matching lines @@
   compiler->SetNeedsStacktrace(catch_try_index());
   compiler->GenerateRuntimeCall(token_pos(),
                                 deopt_id(),
                                 kReThrowRuntimeEntry,
                                 2,
                                 locs());
   __ int3();
 }
 
 
+LocationSummary* StopInstr::MakeLocationSummary(Zone* zone,
+                                                bool opt) const {
+  return new(zone) LocationSummary(zone, 0, 0, LocationSummary::kNoCall);
+}
+
+
+void StopInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
+  __ Stop(message());
+}
+
+
 void GraphEntryInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   if (!compiler->CanFallThroughTo(normal_entry())) {
     __ jmp(compiler->GetJumpLabel(normal_entry()));
   }
 }
 
 
 LocationSummary* GotoInstr::MakeLocationSummary(Zone* zone,
                                                 bool opt) const {
   return new(zone) LocationSummary(zone, 0, 0, LocationSummary::kNoCall);
@@ skipping 269 matching lines @@
   __ Drop(1);
   __ popq(result);
 }
 
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64