DOMUI: Use a styled button instead of an image for the password list show/hide

chrome/browser/resources/options/options_page.css

 body {
   cursor: default;
   font-size: 100%;
 }
 
 #settings-title {
   -webkit-padding-end: 24px;
   color: #53637d;
   cursor: pointer;
   font-size: 200%;
@@ skipping 371 matching lines @@
 list:focus > [lead],
 list:focus > [lead][selected],
 list [lead][selected][editing] {
   border-top: 1px solid #7892b4;
   border-bottom: 1px solid #7892b4;
 }
 
 list:focus > [lead]:nth-child(2),
 list:focus > [lead][selected]:nth-child(2),
 list [lead][selected][editing]:nth-child(2) {
-  border-top: 1px transparent;
+  border-top: 1px solid transparent;
 }
 
 list:focus > [lead]:nth-last-child(2),
 list:focus > [lead][selected]:nth-last-child(2),
 list [lead][selected][editing]:nth-last-child(2) {
-  border-bottom: 1px transparent;
+  border-bottom: 1px solid transparent;
 }
 
 list[disabled] > [lead][selected],
 list[disabled]:focus > [lead][selected] {
   border: none;
 }
 
 list[disabled] {
   opacity: 0.6;
 }
@@ skipping 117 matching lines @@
 /* UI Controls */
 
 button:focus,
 input:focus,
 input[type='submit']:focus,
 select:focus {
   outline-color: rgba(0, 128, 256, 0.5);
 }
 
 /* TEXT */
+input[type='password],
 input[type='text'] {
   -webkit-border-radius: 2px;
   border: 1px solid #aaa;
   font-size: inherit;
   padding: 3px;
 }
 
 /* BUTTON */
 button,
 input[type='submit'] {
@@ skipping 87 matching lines @@
 }
 
 html[os=mac] label > input[type=checkbox],
 html[os=mac] label > input[type=radio] {
   margin-top: 2px;
 }
 
 .suboption {
   -webkit-margin-start: 16px;
 }