Let NaN flow as double into HBranch

src/ia32/lithium-ia32.cc

Index: src/ia32/lithium-ia32.cc
diff --git a/src/ia32/lithium-ia32.cc b/src/ia32/lithium-ia32.cc
index 706e031d9f21fd13498974c85220dee0402b935d..901b2f2258c8f8d9375d042645a264474d433e45 100644
--- a/src/ia32/lithium-ia32.cc
+++ b/src/ia32/lithium-ia32.cc
@@ -1060,15 +1060,17 @@ LInstruction* LChunkBuilder::DoBranch(HBranch* instr) {
     return new(zone()) LGoto(successor->block_id());
   }
 
+  ToBooleanStub::Types expected = instr->expected_input_types();
+
   // Untagged integers or doubles, smis and booleans don't require a
   // deoptimization environment nor a temp register.
   Representation rep = value->representation();
   HType type = value->type();
-  if (!rep.IsTagged() || type.IsSmi() || type.IsBoolean()) {
+  if (!rep.IsTagged() || type.IsSmi() || type.IsBoolean() ||
+      expected == ToBooleanStub::all_types()) {
     return new(zone()) LBranch(UseRegister(value), NULL);
   }
 
-  ToBooleanStub::Types expected = instr->expected_input_types();
   // We need a temporary register when we have to access the map *or* we have
   // no type info yet, in which case we handle all cases (including the ones
   // involving maps).