Remove ::first-letter and ::first-line selectors from print styles

Bootstrap itself doesn't use any `::first-letter` or `::first-line`
styles. These selectors also cause(d) problems in IE11 (see
https://github.com/h5bp/html5-boilerplate/pull/1799) and currently cause
a nasty rendering bug in Chrome where the first letter is vertically
shifted (see https://github.com/twbs/bootstrap/issues/21771)

As h5bp has now removed these as well, no need to keep and comment them
out. See https://github.com/h5bp/html5-boilerplate/issues/1961 /
https://github.com/h5bp/html5-boilerplate/pull/1962

scss/_print.scss

@@ -12,15 +12,7 @@
   @media print {
     *,
     *::before,
-    *::after,
-    p::first-letter,
-    div::first-letter,
-    blockquote::first-letter,
-    li::first-letter,
-    p::first-line,
-    div::first-line,
-    blockquote::first-line,
-    li::first-line {
+    *::after {
       // Bootstrap specific; comment out `color` and `background`
       //color: #000 !important; // Black prints faster:
                                 //   http://www.sanbeiji.com/archives/953