Reland r22082 "Replace HeapNumber as doublebox with an explicit MutableHeapNumber."

src/factory.h

 // 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.
 
 #ifndef V8_FACTORY_H_
 #define V8_FACTORY_H_
 
 #include "src/isolate.h"
 
 namespace v8 {
@@ skipping 334 matching lines @@
                                   PretenureFlag pretenure = NOT_TENURED);
   Handle<Object> NewNumberFromSize(size_t value,
                                    PretenureFlag pretenure = NOT_TENURED) {
     if (Smi::IsValid(static_cast<intptr_t>(value))) {
       return Handle<Object>(Smi::FromIntptr(static_cast<intptr_t>(value)),
                             isolate());
     }
     return NewNumber(static_cast<double>(value), pretenure);
   }
   Handle<HeapNumber> NewHeapNumber(double value,
+                                   MutableMode mode = IMMUTABLE,
                                    PretenureFlag pretenure = NOT_TENURED);
 
-
   // These objects are used by the api to create env-independent data
   // structures in the heap.
   inline Handle<JSObject> NewNeanderObject() {
     return NewJSObjectFromMap(neander_map());
   }
 
   Handle<JSObject> NewArgumentsObject(Handle<Object> callee, int length);
 
   // JS objects are pretenured when allocated by the bootstrapper and
   // runtime.
@@ skipping 342 matching lines @@
                                  PretenureFlag pretenure = TENURED);
 
   Handle<JSFunction> NewFunction(Handle<Map> map,
                                  Handle<String> name,
                                  MaybeHandle<Code> maybe_code);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_FACTORY_H_