Inline HeapNumber::HeapNumberBooleanValue(), only used in objects.cc.

R=cbruni@chromium.org

Bug: 
Change-Id: Id1993e64375084e43479c20607a5c20778117ecc
Reviewed-on: https://chromium-review.googlesource.com/601910Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47215}

src/objects.cc

@@ -457,7 +457,7 @@ bool Object::BooleanValue() {
   if (IsNullOrUndefined(isolate)) return false;
   if (IsUndetectable()) return false;  // Undetectable object is false.
   if (IsString()) return String::cast(this)->length() != 0;
-  if (IsHeapNumber()) return HeapNumber::cast(this)->HeapNumberBooleanValue();
+  if (IsHeapNumber()) return DoubleToBoolean(HeapNumber::cast(this)->value());
   return true;
 }
 
@@ -3467,12 +3467,6 @@ bool HeapObject::IsValidSlot(int offset) {
                                                     this, offset, 0);
 }
 
-
-bool HeapNumber::HeapNumberBooleanValue() {
-  return DoubleToBoolean(value());
-}
-
-
 void HeapNumber::HeapNumberPrint(std::ostream& os) {  // NOLINT
   os << value();
 }

src/objects.h

@@ -1883,9 +1883,6 @@ class HeapNumber: public HeapObject {
 
   DECL_CAST(HeapNumber)
 
-  // Dispatched behavior.
-  bool HeapNumberBooleanValue();
-
   V8_EXPORT_PRIVATE void HeapNumberPrint(std::ostream& os);  // NOLINT
   DECL_VERIFIER(HeapNumber)