Stop adapting the arguments passed to the builtin implementations...

src/builtins-arm.cc

Index: src/builtins-arm.cc
===================================================================
--- src/builtins-arm.cc	(revision 311)
+++ src/builtins-arm.cc	(working copy)
@@ -40,12 +40,21 @@
 void Builtins::Generate_Adaptor(MacroAssembler* masm,
                                 int argc,
                                 CFunctionId id) {
-  // r0 contains the number of arguments excluding the receiver.
-  // JumpToBuiltin expects r0 to contains the number of arguments
-  // including the receiver.
-  __ mov(r0, Operand(argc + 1));
+  // TODO(1238487): Don't pass the function in a static variable.
   __ mov(ip, Operand(ExternalReference::builtin_passed_function()));
   __ str(r1, MemOperand(ip, 0));
+
+  if (argc == -1) {
+    // The actual argument count has already been loaded into register
+    // r0, but JumpToBuiltin expects r0 to contain the number of
+    // arguments including the receiver.
+    __ add(r0, r0, Operand(1));
+  } else {
+    // The number passed in argc excludes the receiver, but
+    // JumpToBuiltin expects r0 to contain the number of arguments
+    // including the receiver.
+    __ mov(r0, Operand(argc + 1));
+  }
   __ JumpToBuiltin(ExternalReference(id));
 }