fix(textarea): Start at a height of one line

Change min-height for textarea to one line height (and remove extra
padding space), and set rows=“1”, since it defaults to 2.

Closes #2953. Fixes #2154.

Author: calebegg

src/components/input/input.js

@@ -247,6 +247,7 @@ function inputTextareaDirective($mdUtil, $window, $mdAria) {
       element.on('keydown input', onChangeTextarea);
       element.on('scroll', onScroll);
       angular.element($window).on('resize', onChangeTextarea);
+      element.attr('rows', '1');
 
       scope.$on('$destroy', function() {
         angular.element($window).off('resize', onChangeTextarea);

src/components/input/input.scss

@@ -69,7 +69,7 @@ md-input-container {
   }
 
   textarea.md-input {
-    min-height: 2 * $input-line-height + $input-border-width-focused + $input-padding-top;
+    min-height: $input-line-height;
     -ms-flex-preferred-size: auto; //IE fix
   }