[Autofill] Add a separate enumeration for HTML field type hints.

chrome/test/data/autofill/heuristics/input/01_autocomplete_attribute_basic.html

 <form action="autocompletetype.html" method="post">
   <!-- Includes all of the tokens from
        http://www.whatwg.org/specs/web-apps/current-work/multipage/association-of-controls-and-forms.html#autofilling-form-controls:-the-autocomplete-attribute
        in their listed order. -->
   <input id="na" autocomplete="name"><br>
   <input id="np" autocomplete="honorific-prefix"><br>
   <input id="ng" autocomplete="given-name"><br>
   <input id="nm" autocomplete="additional-name"><br>
   <input id="n1" autocomplete="additional-name" maxlength="1"><br>
   <input id="nf" autocomplete="family-name"><br>
   <input id="ns" autocomplete="honorific-suffix"><br>
   <input id="nn" autocomplete="nickname"><br>
   <input id="no" autocomplete="organization-title"><br>
   <input id="ao" autocomplete="organization"><br>
   <input id="af" autocomplete="street-address"><br>
   <input id="a1" autocomplete="address-line1"><br>
   <input id="a2" autocomplete="address-line2"><br>
   <input id="a3" autocomplete="address-line3"><br>
   <input id="al" autocomplete="locality"><br>
   <input id="ar" autocomplete="region"><br>
   <input id="ac" autocomplete="country"><br>
+  <input id="an" autocomplete="country-name"><br>
   <input id="ap" autocomplete="postal-code"><br>
   <input id="cn" autocomplete="cc-name"><br>
   <input id="cg" autocomplete="cc-given-name"><br>
   <input id="ca" autocomplete="cc-additional-name"><br>
   <input id="cf" autocomplete="cc-family-name"><br>
   <input id="cc" autocomplete="cc-number"><br>
   <input id="ce" autocomplete="cc-exp"><br>
   <input id="c5" autocomplete="cc-exp" maxlength="5"><br>
+  <input id="c7" autocomplete="cc-exp" maxlength="7"><br>
   <input id="cm" autocomplete="cc-exp-month"><br>
   <input id="cy" autocomplete="cc-exp-year"><br>
   <input id="c2" autocomplete="cc-exp-year" maxlength="2"><br>
+  <input id="c4" autocomplete="cc-exp-year" maxlength="4"><br>
   <input id="cs" autocomplete="cc-csc"><br>
   <input id="ct" autocomplete="cc-type"><br>
   <input id="xl" autocomplete="language"><br>
   <input id="xb" autocomplete="bday"><br>
   <input id="xd" autocomplete="bday-day"><br>
   <input id="xm" autocomplete="bday-month"><br>
   <input id="xy" autocomplete="bday-year"><br>
   <input id="xs" autocomplete="sex"><br>
   <input id="xu" autocomplete="url"><br>
   <input id="xp" autocomplete="photo"><br>
   <input id="em" autocomplete="email"><br>
   <input id="im" autocomplete="impp"><br>
   <input id="tt" autocomplete="tel"><br>
   <input id="tc" autocomplete="tel-country-code"><br>
   <input id="tn" autocomplete="tel-national"><br>
   <input id="ta" autocomplete="tel-area-code"><br>
   <input id="tl" autocomplete="tel-local"><br>
   <input id="tp" autocomplete="tel-local-prefix"><br>
   <input id="ts" autocomplete="tel-local-suffix"><br>
   <input id="te" autocomplete="tel-extension"><br>
 </form>