Revert "fix(autocomplete): show dropdown on top only when there is ro…

…om" (angular#11626)

This reverts commit a37f7cc.

Creating this PR to investigate failure in google3 possibly caused by the reverted change

src/components/autocomplete/js/autocompleteController.js

@@ -143,7 +143,7 @@ function MdAutocompleteCtrl ($scope, $element, $mdUtil, $mdConstant, $mdTheming,
 
     // Automatically determine dropdown placement based on available space in viewport.
     if (!position) {
-      position = (vrect.top + MENU_PADDING > dropdownHeight) ? 'top' : 'bottom';
+      position = (top > bot && root.height - top - MENU_PADDING < dropdownHeight) ? 'top' : 'bottom';
     }
     // Adjust the width to account for the padding provided by `md-input-container`
     if ($attrs.mdFloatingLabel) {