Fix uninitialized variable compiler errors [GCC 4.8.4]

src/runtime/runtime-classes.cc

 // Copyright 2014 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.
 
 #include <stdlib.h>
 #include <limits>
 
 #include "src/v8.h"
 
 #include "src/arguments.h"
@@ skipping 288 matching lines @@
 }
 
 
 RUNTIME_FUNCTION(Runtime_LoadKeyedFromSuper) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 3);
   CONVERT_ARG_HANDLE_CHECKED(Object, receiver, 0);
   CONVERT_ARG_HANDLE_CHECKED(JSObject, home_object, 1);
   CONVERT_ARG_HANDLE_CHECKED(Object, key, 2);
 
-  uint32_t index;
+  uint32_t index = 0;
   if (key->ToArrayIndex(&index)) {
     return LoadElementFromSuper(isolate, receiver, home_object, index);
   }
 
   Handle<Name> name;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, name,
                                      Runtime::ToName(isolate, key));
   if (name->AsArrayIndex(&index)) {
     return LoadElementFromSuper(isolate, receiver, home_object, index);
   }
@@ skipping 67 matching lines @@
   CONVERT_ARG_HANDLE_CHECKED(Object, value, 3);
 
   return StoreToSuper(isolate, home_object, receiver, name, value, SLOPPY);
 }
 
 
 static Object* StoreKeyedToSuper(Isolate* isolate, Handle<JSObject> home_object,
                                  Handle<Object> receiver, Handle<Object> key,
                                  Handle<Object> value,
                                  LanguageMode language_mode) {
-  uint32_t index;
+  uint32_t index = 0;
 
   if (key->ToArrayIndex(&index)) {
     return StoreElementToSuper(isolate, home_object, receiver, index, value,
                                language_mode);
   }
   Handle<Name> name;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, name,
                                      Runtime::ToName(isolate, key));
   if (name->AsArrayIndex(&index)) {
     return StoreElementToSuper(isolate, home_object, receiver, index, value,
@@ skipping 46 matching lines @@
   return nullptr;
 }
 
 
 RUNTIME_FUNCTION(Runtime_CallSuperWithSpread) {
   UNIMPLEMENTED();
   return nullptr;
 }
 }  // namespace internal
 }  // namespace v8