Optimize expressions of the form (expr === true) when expr has boolean type.

vm/il_printer.cc

Index: vm/il_printer.cc
===================================================================
--- vm/il_printer.cc	(revision 10497)
+++ vm/il_printer.cc	(working copy)
@@ -11,6 +11,7 @@
 namespace dart {
 
 DEFINE_FLAG(bool, print_environments, false, "Print SSA environments.");
+DEFINE_FLAG(bool, print_types, false, "Print propagated types.");
 
 
 void BufferFormatter::Print(const char* format, ...) {
@@ -428,6 +429,11 @@
     if (i < inputs_.length() - 1) f->Print(", ");
   }
   f->Print(")");
+  if (FLAG_print_types && HasPropagatedType()) {
+    f->Print(", propatated_type_=%s",
+             String::Handle(AbstractType::Handle(
+                 PropagatedType()).Name()).ToCString());
+  }
 }
 
 
@@ -461,6 +467,11 @@
     f->Print("    t%d <- ", temp_index());
   }
   computation()->PrintTo(f);
+  if (FLAG_print_types && HasPropagatedType()) {
+    f->Print(", propatated_type_=%s",
+             String::Handle(AbstractType::Handle(
+                 PropagatedType()).Name()).ToCString());
+  }
 }