[turbofan] Improve typing of ToBoolean.

src/compiler/typer.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/bootstrapper.h"
 #include "src/compiler/graph-inl.h"
 #include "src/compiler/graph-reducer.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/node.h"
 #include "src/compiler/node-properties-inl.h"
@@ skipping 169 matching lines @@
   singleton_zero = Type::Range(zero, zero, zone);
   singleton_one = Type::Range(one, one, zone);
   zero_or_one = Type::Union(singleton_zero, singleton_one, zone);
   zeroish = Type::Union(singleton_zero, nan_or_minuszero, zone);
   signed32ish = Type::Union(signed32, truncating_to_zero, zone);
   unsigned32ish = Type::Union(unsigned32, truncating_to_zero, zone);
   falsish = Type::Union(Type::Undetectable(),
                         Type::Union(Type::Union(singleton_false, zeroish, zone),
                                     undefined_or_null, zone),
                         zone);
+  truish = Type::Union(
+      singleton_true,
+      Type::Union(Type::DetectableReceiver(), Type::Symbol(), zone), zone);
   integer = Type::Range(minusinfinity, infinity, zone);
   weakint = Type::Union(integer, nan_or_minuszero, zone);
 
   number_fun0_ = Type::Function(number, zone);
   number_fun1_ = Type::Function(number, number, zone);
   number_fun2_ = Type::Function(number, number, number, zone);
 
   weakint_fun1_ = Type::Function(weakint, number, zone);
   random_fun_ = Type::Function(Type::OrderedNumber(), zone);
 
@@ skipping 306 matching lines @@
   if (type->Is(Type::Primitive()) && !type->Maybe(Type::Receiver())) {
     return type;
   }
   return Type::Primitive();
 }
 
 
 Type* Typer::Visitor::ToBoolean(Type* type, Typer* t) {
   if (type->Is(Type::Boolean())) return type;
   if (type->Is(t->falsish)) return t->singleton_false;
-  if (type->Is(Type::DetectableReceiver())) return t->singleton_true;
-  if (type->Is(Type::OrderedNumber()) && (type->Max() < 0 || 0 < type->Min())) {
+  if (type->Is(t->truish)) return t->singleton_true;
+  if (type->Is(Type::PlainNumber()) && (type->Max() < 0 || 0 < type->Min())) {
     return t->singleton_true;  // Ruled out nan, -0 and +0.
   }
   return Type::Boolean();
 }
 
 
 Type* Typer::Visitor::ToNumber(Type* type, Typer* t) {
   if (type->Is(Type::Number())) return type;
   if (type->Is(Type::Null())) return t->singleton_zero;
   if (type->Is(Type::Undefined())) return Type::NaN();
@@ skipping 1566 matching lines @@
         // TODO(rossberg): Do we want some ClampedArray type to express this?
         break;
     }
   }
   return Type::Constant(value, zone());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8