X87: [stubs] Introduce a dedicated FastNewObjectStub.

src/x87/macro-assembler-x87.h

Index: src/x87/macro-assembler-x87.h
diff --git a/src/x87/macro-assembler-x87.h b/src/x87/macro-assembler-x87.h
index a51e951b0a45837e6997a8c688d568c4a9b6ab1d..fc493610c438bd5ad70c2f40539d60219668ed59 100644
--- a/src/x87/macro-assembler-x87.h
+++ b/src/x87/macro-assembler-x87.h
@@ -529,6 +529,9 @@ class MacroAssembler: public Assembler {
   // enabled via --debug-code.
   void AssertBoundFunction(Register object);
 
+  // Abort execution if argument is not a JSReceiver, enabled via --debug-code.
+  void AssertReceiver(Register object);
+
   // Abort execution if argument is not undefined or an AllocationSite, enabled
   // via --debug-code.
   void AssertUndefinedOrAllocationSite(Register object);