[builtins] Migrate Number constructor similar to String constructor.

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index 179ed66b0d81b9763a5778347ce25e57826c0f11..9952eb3b659678f11768997de16e269637575458 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -4940,6 +4940,27 @@ void MacroAssembler::AllocateOneByteSlicedString(Register result,
 }
 
 
+void MacroAssembler::AllocateJSValue(Register result, Register constructor,
+                                     Register value, Register scratch,
+                                     Label* gc_required) {
+  DCHECK(!result.is(constructor));
+  DCHECK(!result.is(scratch));
+  DCHECK(!result.is(value));
+
+  // Allocate JSValue in new space.
+  Allocate(JSValue::kSize, result, scratch, no_reg, gc_required, TAG_OBJECT);
+
+  // Initialize the JSValue.
+  LoadGlobalFunctionInitialMap(constructor, scratch);
+  movp(FieldOperand(result, HeapObject::kMapOffset), scratch);
+  LoadRoot(scratch, Heap::kEmptyFixedArrayRootIndex);
+  movp(FieldOperand(result, JSObject::kPropertiesOffset), scratch);
+  movp(FieldOperand(result, JSObject::kElementsOffset), scratch);
+  movp(FieldOperand(result, JSValue::kValueOffset), value);
+  STATIC_ASSERT(JSValue::kSize == 4 * kPointerSize);
+}
+
+
 // Copy memory, byte-by-byte, from source to destination.  Not optimized for
 // long or aligned copies.  The contents of scratch and length are destroyed.
 // Destination is incremented by length, source, length and scratch are