Autofill: Make the iOS nameForAutofill() match Blink.

ios/web/web_state/js/resources/common.js

 // Copyright 2013 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.
 
 // This file provides common methods that can be shared by other JavaScripts.
 
 goog.provide('__crWeb.common');
 
 goog.require('__crWeb.base');
 
@@ skipping 410 matching lines @@
     if (trimmedName) {
       trimmedName = __gCrWeb.common.trim(trimmedName);
       if (trimmedName.length > 0) {
         return trimmedName;
       }
     }
     trimmedName = element.getAttribute('id');
     if (trimmedName) {
       return __gCrWeb.common.trim(trimmedName);
     }
-    trimmedName = element.getAttribute('autocomplete');

[Lei Zhang, 2015/05/09 01:46:53]

https://chromereviews.googleplex.com/19497013 which added this is wrong IMO due
to the incorrect changes it made to the autocomplete_attribute_invalid test
expectations.

__gCrWeb.autofill.webFormControlElementToFormField() also calls
element.getAttribute('autocomplete') and all the autocomplete_attribute
heuristics tests passes at ToT. Perhaps it was broken before, so Jim felt this
was the correct solution, but it's simply not needed now.

-    if (trimmedName && trimmedName !== 'off') {
-      return __gCrWeb.common.trim(trimmedName);
-    }
-    trimmedName = element.getAttribute('placeholder');

[Lei Zhang, 2015/05/09 01:46:53]

For placeholder, AKA crbug.com/325206, upstream eventually implemented the same
feature in https://codereview.chromium.org/675883002, which then got ported to
autofill_controller.js in https://chromereviews.googleplex.com/112877013. The
20_checkout_staples.com.html test case would fail if we didn't consider the
placeholder attribute.

-    if (trimmedName) {
-      return __gCrWeb.common.trim(trimmedName);
-    }
     return '';
   };
 
   /**
    * Acquires the specified DOM |attribute| from the DOM |element| and returns
    * its lower-case value, or null if not present.
    * @param {Element} element A DOM element.
    * @param {string} attribute An attribute name.
    * @return {?string} Lowercase value of DOM element or null if not present.
    */
@@ skipping 237 matching lines @@
     var plugins = findPluginNodesWithoutFallback_();
     if (plugins.length > 0) {
       // Store the list of plugins in a known place for the replacement script
       // to use, then trigger it.
       __gCrWeb['placeholderTargetPlugins'] = plugins;
       return true;
     }
     return false;
   };
 }  // End of anonymous object