Copy-to-clipboard fix (#4190)

* Copy-to-clipboard fix

target.setSelectionRange(0, target.value.length); does not always seem to be
working. It doesn't work once the text is unselected. Using textarea.select()
function: https://developer.mozilla.org/en-US/docs/Web/API/HTMLInputElement/select

Fixes #3965.

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

* Empty commit

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

js/script.js

@@ -25,7 +25,7 @@ function copyCode(elem){
              }
              target.value = document.getElementById(elem).innerText;
          // select the content
-         target.setSelectionRange(0, target.value.length);
+         target.select();
 
          // copy the selection
          var succeed;