Make the strict-mode calling convention for contextual calls the default one.

src/x64/ic-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 980 matching lines @@
     Label invoke, global;
     __ movq(rdx, args.GetReceiverOperand());
     __ JumpIfSmi(rdx, &invoke);
     __ CmpObjectType(rdx, JS_GLOBAL_OBJECT_TYPE, rcx);
     __ j(equal, &global);
     __ CmpInstanceType(rcx, JS_BUILTINS_OBJECT_TYPE);
     __ j(not_equal, &invoke);
 
     // Patch the receiver on the stack.
     __ bind(&global);
-    CallStubCompiler::FetchGlobalProxy(masm, rdx, rdi);
+    __ LoadRoot(rdx, Heap::kUndefinedValueRootIndex);
     __ movq(args.GetReceiverOperand(), rdx);
     __ bind(&invoke);
   }
 
   // Invoke the function.
   CallKind call_kind = CallICBase::Contextual::decode(extra_state)
       ? CALL_AS_FUNCTION
       : CALL_AS_METHOD;
   ParameterCount actual(argc);
   __ InvokeFunction(rdi,
@@ skipping 687 matching lines @@
   Condition cc = (check == ENABLE_INLINED_SMI_CHECK)
       ? (*jmp_address == Assembler::kJncShortOpcode ? not_zero : zero)
       : (*jmp_address == Assembler::kJnzShortOpcode ? not_carry : carry);
   *jmp_address = static_cast<byte>(Assembler::kJccShortPrefix | cc);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64