Model exceptional edges from call nodes in TurboFan.

src/compiler/operator.h

Index: src/compiler/operator.h
diff --git a/src/compiler/operator.h b/src/compiler/operator.h
index 6407499da5515759df53363087831c4dc44c01d5..114cf6aff577d02a8cea2740c4ef13ca70468fac 100644
--- a/src/compiler/operator.h
+++ b/src/compiler/operator.h
@@ -97,6 +97,10 @@ class Operator : public ZoneObject {
   int EffectOutputCount() const { return effect_out_; }
   int ControlOutputCount() const { return control_out_; }
 
+  static size_t ZeroIfNoThrow(Properties properties) {
+    return (properties & kNoThrow) == kNoThrow ? 0 : 2;
+  }
+
   static size_t ZeroIfPure(Properties properties) {
     return (properties & kPure) == kPure ? 0 : 1;
   }