fix(select): prevent labels from overflowing

Prevents the select labels from overflowing their parent.

Closes #7865.

Author: crisbeto

src/components/select/select.scss

@@ -109,7 +109,7 @@ md-select {
   }
 
   *:first-child {
-    flex: 1 0 auto;
+    flex: 1 1 auto;
     text-overflow: ellipsis;
     white-space: nowrap;
     overflow: hidden;