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

ios/web/web_state/js/common_js_unittest.mm

 // Copyright 2015 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.
 
 #include <stddef.h>
 #import <Foundation/Foundation.h>
 
 #include "base/macros.h"
 #include "base/strings/sys_string_conversions.h"
 #import "ios/web/public/test/web_test_with_web_state.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #import "testing/gtest_mac.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 
 // Struct for isTextField() test data.
 struct TextFieldTestElement {
   // The element name.
   const char* element_name;
   // The index of this element in those that have the same name.
   const int element_index;
   // True if this is expected to be a text field.
   const bool expected_is_text_field;
@@ skipping 108 matching lines @@
     // |webController_| will also inject web_bundle.js.
     LoadHtml(@"<p>");
     id result = ExecuteJavaScript(data.test_script);
     EXPECT_NSEQ(data.expected_value, result)
         << " in test " << i << ": "
         << base::SysNSStringToUTF8(data.test_script);
   }
 }
 
 }  // namespace web