Reapply r18377 it was reverted due to the unrelated bug it surfaced.

runtime/vm/vm_sources.gypi

 # 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.
 
 # This file contains all sources (vm and tests) for the dart virtual machine.
 # Unit test files need to have a '_test' suffix appended to the name.
 {
   'sources': [
     'allocation.cc',
     'allocation.h',
@@ skipping 137 matching lines @@
     'flow_graph_compiler.cc',
     'flow_graph_compiler.h',
     'flow_graph_compiler_arm.cc',
     'flow_graph_compiler_ia32.cc',
     'flow_graph_compiler_mips.cc',
     'flow_graph_compiler_x64.cc',
     'flow_graph_inliner.cc',
     'flow_graph_inliner.h',
     'flow_graph_optimizer.cc',
     'flow_graph_optimizer.h',
+    'flow_graph_type_propagator.cc',
+    'flow_graph_type_propagator.h',
     'freelist.cc',
     'freelist.h',
     'freelist_test.cc',
     'gc_marker.cc',
     'gc_marker.h',
     'gc_sweeper.cc',
     'gc_sweeper.h',
     'gdbjit_android.cc',
     'gdbjit_android.h',
     'gdbjit_linux.cc',
@@ skipping 174 matching lines @@
     'verifier.cc',
     'verifier.h',
     'visitor.h',
     'vtune.cc',
     'vtune.h',
     'zone.cc',
     'zone.h',
     'zone_test.cc',
   ],
 }