Optimize redundant HCompareMap instructions with known successors.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 8f1c62be9ea5cde55773b77300aa4050a5d3d359..c25dff121734a72538da33a13daec2db7110459c 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -1117,6 +1117,11 @@ void HCompareMap::PrintDataTo(StringStream* stream) {
   value()->PrintNameTo(stream);
   stream->Add(" (%p)", *map().handle());
   HControlInstruction::PrintDataTo(stream);
+  if (known_successor_index() == 0) {
+    stream->Add(" [true]");
+  } else if (known_successor_index() == 1) {
+    stream->Add(" [false]");
+  }
 }