Back port r11886: Fix GC bug with missing handle. Bug=133618

src/mips/lithium-codegen-mips.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 2320 matching lines @@
       // Non-negative property indices are in the properties array.
       __ lw(result, FieldMemOperand(object, JSObject::kPropertiesOffset));
       __ lw(result, FieldMemOperand(result, offset + FixedArray::kHeaderSize));
     }
   } else if (lookup.IsFound() && lookup.type() == CONSTANT_FUNCTION) {
     Handle<JSFunction> function(lookup.GetConstantFunctionFromMap(*type));
     __ LoadHeapObject(result, function);
   } else {
     // Negative lookup.
     // Check prototypes.
-    HeapObject* current = HeapObject::cast((*type)->prototype());
+    Handle<HeapObject> current(HeapObject::cast((*type)->prototype()));
     Heap* heap = type->GetHeap();
-    while (current != heap->null_value()) {
-      Handle<HeapObject> link(current);
-      __ LoadHeapObject(result, link);
+    while (*current != heap->null_value()) {
+      __ LoadHeapObject(result, current);
       __ lw(result, FieldMemOperand(result, HeapObject::kMapOffset));
-      DeoptimizeIf(ne, env,
-          result, Operand(Handle<Map>(JSObject::cast(current)->map())));
-      current = HeapObject::cast(current->map()->prototype());
+      DeoptimizeIf(ne, env, result, Operand(Handle<Map>(current->map())));
+      current =
+          Handle<HeapObject>(HeapObject::cast(current->map()->prototype()));
     }
     __ LoadRoot(result, Heap::kUndefinedValueRootIndex);
   }
 }
 
 
 void LCodeGen::DoLoadNamedFieldPolymorphic(LLoadNamedFieldPolymorphic* instr) {
   Register object = ToRegister(instr->object());
   Register result = ToRegister(instr->result());
   Register object_map = scratch0();
@@ skipping 2843 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal