Fix crash in HTMLInputElement::setupDateTimeChooserParameters

LayoutTests/fast/forms/calendar-picker/datepicker-crash-after-keydown.html

Index: LayoutTests/fast/forms/calendar-picker/datepicker-crash-after-keydown.html
diff --git a/LayoutTests/fast/forms/calendar-picker/datepicker-crash-after-keydown.html b/LayoutTests/fast/forms/calendar-picker/datepicker-crash-after-keydown.html
new file mode 100644
index 0000000000000000000000000000000000000000..d8fe81e99af71f73bca18d13e6b776b6c9e8481f
--- /dev/null
+++ b/LayoutTests/fast/forms/calendar-picker/datepicker-crash-after-keydown.html
@@ -0,0 +1,19 @@
+<input id="month" type="month"</div>
+<script>
+  if (window.testRunner) {

[tkent, 2014/08/01 00:10:39]

nit: The top-level indentation is not helpful.

+    testRunner.dumpAsText();
+  }
+  function openPicker(input) {
+    sendKey(input, "Down", false, true);
+    finishTest();
+  }
+  function sendKey(input, keyName, ctrlKey, altKey) {
+    var event = document.createEvent('KeyboardEvent');
+    event.initKeyboardEvent('keydown', true, true, document.defaultView, keyName, 0, ctrlKey, altKey);
+    input.dispatchEvent(event);
+  }
+  openPicker(document.getElementById('month'), finishTest);
+  function finishTest() {
+    document.body.innerText = 'PASS (not crashed)';
+  }
+</script>