optimize generated erb to reduce method calls

before:

        ');@output_buffer.append= ( content_icon row[:content] );@output_buffer.safe_concat('
');@output_buffer.safe_concat('        ');@output_buffer.append= ( spinner_img );@output_buffer.safe_concat('
');@output_buffer.safe_concat('      </td>
      <td class="content">
        ');@output_buffer.append= ( content_link row[:content] );@output_buffer.safe_concat('
');@output_buffer.safe_concat('      </td>
      <td class="message">
');

after:

        ');@output_buffer.append= ( content_icon row[:content] );@output_buffer.safe_concat('
        ');@output_buffer.append= ( spinner_img );@output_buffer.safe_concat('
      </td>
      <td class="content">
        ');@output_buffer.append= ( content_link row[:content] );@output_buffer.safe_concat('
      </td>
      <td class="message">
');