Remove unused 'receiver' field from generators

src/mips/builtins-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_MIPS
 
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 838 matching lines @@
   __ Branch(&skip_flooding, eq, t1, Operand(zero_reg));
   {
     FrameScope scope(masm, StackFrame::INTERNAL);
     __ Push(a1, a2, t0);
     __ CallRuntime(Runtime::kDebugPrepareStepInIfStepping);
     __ Pop(a1, a2);
     __ lw(t0, FieldMemOperand(a1, JSGeneratorObject::kFunctionOffset));
   }
   __ bind(&skip_flooding);
 
-  // Push receiver.
-  __ lw(t1, FieldMemOperand(a1, JSGeneratorObject::kReceiverOffset));
-  __ Push(t1);
+  // Push hole for the never-used receiver, similarly to arguments below.
+  __ PushRoot(Heap::kTheHoleValueRootIndex);
 
   // ----------- S t a t e -------------
   //  -- a1    : the JSGeneratorObject to resume
   //  -- a2    : the resume mode (tagged)
   //  -- t0    : generator function
   //  -- cp    : generator context
   //  -- ra    : return address
   //  -- sp[0] : generator receiver
   // -----------------------------------
 
@@ skipping 2022 matching lines @@
   }
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS