MIPS: ES6 symbols: turn symbols into a proper primitive type

src/mips/stub-cache-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 2406 matching lines @@
           masm(), Context::STRING_FUNCTION_INDEX, a0, &miss);
       CheckPrototypes(
           Handle<JSObject>(JSObject::cast(object->GetPrototype(isolate()))),
           a0, holder, a3, a1, t0, name, &miss);
       break;
 
     case SYMBOL_CHECK:
       // Check that the object is a symbol.
       __ GetObjectType(a1, a1, a3);
       __ Branch(&miss, ne, a3, Operand(SYMBOL_TYPE));
+      // Check that the maps starting from the prototype haven't changed.
+      GenerateDirectLoadGlobalFunctionPrototype(
+          masm(), Context::SYMBOL_FUNCTION_INDEX, a0, &miss);
+      CheckPrototypes(
+          Handle<JSObject>(JSObject::cast(object->GetPrototype(isolate()))),
+          a0, holder, a3, a1, t0, name, &miss);
       break;
 
     case NUMBER_CHECK: {
       Label fast;
       // Check that the object is a smi or a heap number.
       __ JumpIfSmi(a1, &fast);
       __ GetObjectType(a1, a0, a0);
       __ Branch(&miss, ne, a0, Operand(HEAP_NUMBER_TYPE));
       __ bind(&fast);
       // Check that the maps starting from the prototype haven't changed.
@@ skipping 1501 matching lines @@
     TailCallBuiltin(masm, Builtins::kKeyedStoreIC_Slow);
   }
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS