Add Autofill preview support for <select> input fields

LayoutTests/fast/forms/suggested-value.html

Index: LayoutTests/fast/forms/suggested-value.html
diff --git a/LayoutTests/fast/forms/suggested-value.html b/LayoutTests/fast/forms/suggested-value.html
index 988b515cde791f310871684a764910df34dad9a3..f253a9b321b43e48a63f6775955ef4d912132cc6 100644
--- a/LayoutTests/fast/forms/suggested-value.html
+++ b/LayoutTests/fast/forms/suggested-value.html
@@ -4,13 +4,15 @@
 <p id="description">This test setting suggested values on an input element 
 and a textarea element. The dump below should have the "suggested value"
 instead of "initial value".</p>
-<pre><input id="test" type="text" value="initial value"><textarea id="textarea"></textarea></pre>
+<pre><input id="test" type="text" value="initial value"><textarea id="textarea"></textarea><select id="select"><option>CA</option><option>TX</option></select></pre>
 <script src="../../resources/dump-as-markup.js"></script>
 <script>
 
 var input = document.getElementById('test');
 var textarea = document.getElementById('textarea');
 textarea.value = "initial value";
+var select = document.getElementById('select');
+select.selectedIndex = -1;
 var result = document.getElementById('result');
 if (!window.internals)
     testFailed('This test requires internals object');
@@ -20,6 +22,7 @@ else {
 
     internals.setSuggestedValue(input, 'suggested value');
     internals.setSuggestedValue(textarea, 'suggested value');
+    internals.setSuggestedValue(select, 'TX');
 
     Markup.description(document.getElementById('description').textContent)
 
@@ -30,7 +33,16 @@ else {
     addTextResult('input.selectionEnd');
     addTextResult('textarea.value');
     addTextResult('internals.suggestedValue(textarea)');
-    
+    // The selected option value is overwritten by the suggested value.
+    // We make a copy of this selected optioin value as originalValue and
+    // recover it once preview is done. The selectedIndex of <select> is
+    // recovered at the same time. This is a workaround as it looks that
+    // changing the text in display of the select inevitably change the
+    // selected index, hence the value of the selected option.
+    addTextResult('select.value');
+    addTextResult('internals.originalValue(select)');
+    addTextResult('internals.suggestedValue(select)');
+
     Markup.dump(input.parentNode);
 }