[stubs] Introduce a dedicated FastNewObjectStub.

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 85ff61d825545aaa48fe8520689f202141ef4d5b..e72d40b4aec743f4db9f5a27a81d25c2d5657010 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -3952,6 +3952,19 @@ void MacroAssembler::AssertBoundFunction(Register object) {
 }
 
 
+void MacroAssembler::AssertReceiver(Register object) {
+  if (emit_debug_code()) {
+    testb(object, Immediate(kSmiTagMask));
+    Check(not_equal, kOperandIsASmiAndNotAReceiver);
+    Push(object);
+    STATIC_ASSERT(LAST_TYPE == LAST_JS_RECEIVER_TYPE);
+    CmpObjectType(object, FIRST_JS_RECEIVER_TYPE, object);
+    Pop(object);
+    Check(above_equal, kOperandIsNotAReceiver);
+  }
+}
+
+
 void MacroAssembler::AssertUndefinedOrAllocationSite(Register object) {
   if (emit_debug_code()) {
     Label done_checking;