[ObjC ARC] Converts ios/web:earl_grey_test_support to ARC.

ios/web/public/test/earl_grey/js_test_util.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef IOS_WEB_PUBLIC_TEST_EARL_GREY_JS_TEST_UTIL_H_
 #define IOS_WEB_PUBLIC_TEST_EARL_GREY_JS_TEST_UTIL_H_
 
 #import <Foundation/Foundation.h>
 
 #import "ios/web/public/web_state/web_state.h"
 
 namespace web {
 
 // Waits until the Window ID has been injected and the page is thus ready to
 // respond to JavaScript injection. Fails with a GREYAssert on timeout or if
 // unrecoverable error (such as no web view) occurs.
 void WaitUntilWindowIdInjected(WebState* web_state);
 
 // Executes |javascript| on the given |web_state|, and waits until execution is
 // completed. If |out_error| is not nil, it is set to the error resulting from
 // the execution, if one occurs. The return value is the result of the
 // JavaScript execution. If the script execution is timed out, then this method
 // fails with a GREYAssert.
 id ExecuteJavaScript(WebState* web_state,
                      NSString* javascript,
-                     NSError** out_error);
+                     NSError* __autoreleasing* out_error);

[baxley, 2017/05/16 20:12:48]

This is one of the more interesting things I did. Let me know if you have
thoughts/concerns.

[stkhapugin, 2017/05/30 13:21:38]

This looks right to me. 

 
 // Synchronously returns the result of executed JavaScript on interstitial page
 // displayed for |web_state|.
 id ExecuteScriptOnInterstitial(WebState* web_state, NSString* script);
 
 }  // namespace web
 
 #endif  // IOS_WEB_PUBLIC_TEST_EARL_GREY_JS_TEST_UTIL_H_