Omit unreachable fall through code for graph intrinsics, e.g. Array.length.

runtime/vm/flow_graph_compiler.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_XXX.
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
@@ skipping 1154 matching lines @@
       if (FLAG_precompiled_mode ||
           (store_node.field().guarded_cid() == kDynamicCid)) {
         GenerateInlinedSetter(store_node.field().Offset());
         return !FLAG_use_field_guards;
       }
     }
   }
 
   EnterIntrinsicMode();
 
-  Intrinsifier::Intrinsify(parsed_function(), this);
+  bool complete = Intrinsifier::Intrinsify(parsed_function(), this);
 
   ExitIntrinsicMode();
+
   // "Deoptimization" from intrinsic continues here. All deoptimization
   // branches from intrinsic code redirect to here where the slow-path
   // (normal function body) starts.
   // This means that there must not be any side-effects in intrinsic code
   // before any deoptimization point.
   ASSERT(!intrinsic_slow_path_label_.IsBound());
   assembler()->Bind(&intrinsic_slow_path_label_);
-  return false;
+  return complete;
 }
 
 
 // DBC is very different from other architectures in how it performs instance
 // and static calls because it does not use stubs.
 #if !defined(TARGET_ARCH_DBC)
 void FlowGraphCompiler::GenerateInstanceCall(
     intptr_t deopt_id,
     TokenPosition token_pos,
     intptr_t argument_count,
@@ skipping 806 matching lines @@
 
 
 void FlowGraphCompiler::FrameStateClear() {
   ASSERT(!is_optimizing());
   frame_state_.TruncateTo(0);
 }
 #endif  // defined(DEBUG) && !defined(TARGET_ARCH_DBC)
 
 
 }  // namespace dart