fix(input): textarea auto grow fixed

*  Textarea should grow automatically if no `rows` attribute is specified.
*  Texarea should stay fixed with given `rows` attribute (no growing or shrinking)

Fixes #5627. Closes #5636.

Author: devversion

src/components/input/demoBasicUsage/index.html

@@ -77,7 +77,7 @@
 
       <md-input-container class="md-block">
         <label>Biography</label>
-        <textarea ng-model="user.biography" columns="1" md-maxlength="150"></textarea>
+        <textarea ng-model="user.biography" columns="1" md-maxlength="150" rows="5"></textarea>
       </md-input-container>
 
 

src/components/input/input.js

@@ -322,8 +322,9 @@ function inputTextareaDirective($mdUtil, $window, $mdAria) {
             node.style.minHeight = null;
           }
 
-          var rows = Math.max(min_rows, Math.round(node.scrollHeight / lineHeight));
+          var rows = Math.min(min_rows, Math.round(node.scrollHeight / lineHeight));
           node.setAttribute("rows", rows);
+          node.style.height = lineHeight * rows + "px";
         }
 
         // reset everything back to normal