[turbofan] Introduce Oddball::to_number_raw and use it for change lowering.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 326bb24b76935abee9c0a4d8b36ec1db766bbf7c..065980a64af35a6c095922a0ad0ae977436aa86a 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -9433,6 +9433,10 @@ class VectorIterator {
 // The Oddball describes objects null, undefined, true, and false.
 class Oddball: public HeapObject {
  public:
+  // [to_number_raw]: Cached raw to_number computed at startup.
+  inline double to_number_raw() const;
+  inline void set_to_number_raw(double value);
+
   // [to_string]: Cached to_string computed at startup.
   DECL_ACCESSORS(to_string, String)
 
@@ -9462,7 +9466,8 @@ class Oddball: public HeapObject {
                          bool to_boolean, const char* type_of, byte kind);
 
   // Layout description.
-  static const int kToStringOffset = HeapObject::kHeaderSize;
+  static const int kToNumberRawOffset = HeapObject::kHeaderSize;
+  static const int kToStringOffset = kToNumberRawOffset + kDoubleSize;
   static const int kToNumberOffset = kToStringOffset + kPointerSize;
   static const int kToBooleanOffset = kToNumberOffset + kPointerSize;
   static const int kTypeOfOffset = kToBooleanOffset + kPointerSize;
@@ -9484,6 +9489,7 @@ class Oddball: public HeapObject {
   typedef FixedBodyDescriptor<kToStringOffset, kTypeOfOffset + kPointerSize,
                               kSize> BodyDescriptor;
 
+  STATIC_ASSERT(kToNumberRawOffset == HeapNumber::kValueOffset);
   STATIC_ASSERT(kKindOffset == Internals::kOddballKindOffset);
   STATIC_ASSERT(kNull == Internals::kNullOddballKind);
   STATIC_ASSERT(kUndefined == Internals::kUndefinedOddballKind);