html: Fix code block export (superfluous newlines)

I didn't consider that all newlines in the pre block will be printed and we
thus shouldn't wrap html that has it's tags on separate lines (i.e. contains
superfluous newlines) - wrapping in a div less accurately represents
org-html-export but it provides the same information and gives us more freedom
in the return value of HighlightCodeBlock as well as allowing us to keep the
html tags on new lines (consistency).

org/html_writer.go

@@ -59,7 +59,7 @@ func NewHTMLWriter() *HTMLWriter {
 		log:        defaultConfig.Log,
 		htmlEscape: true,
 		HighlightCodeBlock: func(source, lang string) string {
-			return fmt.Sprintf("%s\n<pre>\n%s\n</pre>\n</div>", `<div class="highlight">`, html.EscapeString(source))
+			return fmt.Sprintf("<div class=\"highlight\">\n<pre>\n%s\n</pre>\n</div>", html.EscapeString(source))
 		},
 		footnotes: footnotes{
 			mapping: map[string]int{},
@@ -109,7 +109,7 @@ func (w *HTMLWriter) WriteBlock(b Block) {
 			lang = strings.ToLower(b.Parameters[0])
 		}
 		content = w.HighlightCodeBlock(content, lang)
-		w.WriteString(fmt.Sprintf("<pre class=\"src src-%s\">\n%s\n</pre>\n", lang, content))
+		w.WriteString(fmt.Sprintf("<div class=\"src src-%s\">\n%s\n</div>\n", lang, content))
 	case name == "EXAMPLE":
 		w.WriteString(`<pre class="example">` + "\n" + content + "\n</pre>\n")
 	case name == "EXPORT" && len(b.Parameters) >= 1 && strings.ToLower(b.Parameters[0]) == "html":

org/testdata/blocks.html

@@ -1,5 +1,5 @@
 <figure>
-<pre class="src src-bash">
+<div class="src src-bash">
 <div class="highlight">
 <pre>
 echo &#34;a bash source block&#34;
@@ -11,18 +11,18 @@ function hello {
 hello
 </pre>
 </div>
-</pre>
+</div>
 <figcaption>
 block caption
 </figcaption>
 </figure>
-<pre class="src src-text">
+<div class="src src-text">
 <div class="highlight">
 <pre>
 a source block without a language
 </pre>
 </div>
-</pre>
+</div>
 <pre class="example">
 an example block with
 multiple lines including
@@ -124,13 +124,13 @@ this unindented line is outside of the list item
 <p>
 list item 2
 </p>
-<pre class="src src-text">
+<div class="src src-text">
 <div class="highlight">
 <pre>
 #+BEGIN_EXAMPLE
 </pre>
 </div>
-</pre>
+</div>
 <p>
 #+END_EXAMPLE
 </p>

org/testdata/captions.html

@@ -2,13 +2,13 @@
 Anything can be captioned.
 </p>
 <figure>
-<pre class="src src-sh">
+<div class="src src-sh">
 <div class="highlight">
 <pre>
 echo &#34;i have a caption!&#34;
 </pre>
 </div>
-</pre>
+</div>
 <figcaption>
 captioned soure block
 </figcaption>

org/testdata/footnotes.html

@@ -75,13 +75,13 @@ and other elements
 <p>
 like blocks
 </p>
-<pre class="src src-text">
+<div class="src src-text">
 <div class="highlight">
 <pre>
 other non-plain
 </pre>
 </div>
-</pre>
+</div>
 </li>
 <li>
 <p>

org/testdata/headlines.html

@@ -68,11 +68,11 @@ headline with custom status
 <p>
 it&#39;s possible to use <code class="verbatim">#+SETUPFILE</code> - in this case the setup file contains the following
 </p>
-<pre class="src src-org">
+<div class="src src-org">
 <div class="highlight">
 <pre>
 #+TODO: TODO DONE CUSTOM
 #+EXCLUDE_TAGS: noexport custom_noexport
 </pre>
 </div>
-</pre>
+</div>

org/testdata/keywords.html

@@ -1,9 +1,10 @@
 <figure>
-<pre class="src src-sh a b c d" id="it"><div class="highlight">
+<div class="src src-sh a b c d" id="it">
+<div class="highlight">
 <pre>echo &#34;a bash source block with custom html attributes&#34;
 </pre>
 </div>
-</pre>
+</div>
 <figcaption>
 and <span style="text-decoration: underline;">multiple</span> lines of <strong>captions</strong>!
 </figcaption>

org/testdata/lists.html

@@ -59,13 +59,13 @@ and some lines of text
 <p>
 and another subitem
 </p>
-<pre class="src src-sh">
+<div class="src src-sh">
 <div class="highlight">
 <pre>
 echo with a block
 </pre>
 </div>
-</pre>
+</div>
 </li>
 <li>
 <p>
@@ -133,13 +133,13 @@ term<dd>
 details on a new line (with an empty line in between)
 <strong>continued</strong>
 </p>
-<pre class="src src-bash">
+<div class="src src-bash">
 <div class="highlight">
 <pre>
 echo &#34;Hello World!&#34;
 </pre>
 </div>
-</pre>
+</div>
 <dd>
 </dl>
 <p>

org/testdata/misc.html

@@ -114,7 +114,7 @@ for now files can be included as:
 <p>
 src block
 </p>
-<pre class="src src-org">
+<div class="src src-org">
 <div class="highlight">
 <pre>
 #+SETUPFILE: setup_file_org
@@ -147,7 +147,7 @@ this headline and it&#39;s content are not exported as it is marked with an =EXC
 By default =EXCLUDE_TAGS= is just =:noexport:=.
 </pre>
 </div>
-</pre>
+</div>
 </li>
 <li>
 <p>
@@ -392,13 +392,13 @@ inline code <code class="verbatim">--</code> <code class="verbatim">---</code> a
 <p>
 src/example/export blocks should not be converted!
 </p>
-<pre class="src src-sh">
+<div class="src src-sh">
 <div class="highlight">
 <pre>
 --, ---
 </pre>
 </div>
-</pre>
+</div>
 <pre class="example">
 --, ---
 </pre>
@@ -427,25 +427,25 @@ The behaviour of Org mode <code class="verbatim">&lt;s TAB</code> changed and it
 <p>
 lowercased:
 </p>
-<pre class="src src-bash">
+<div class="src src-bash">
 <div class="highlight">
 <pre>
 uname -a
 </pre>
 </div>
-</pre>
+</div>
 </li>
 <li>
 <p>
 uppercased
 </p>
-<pre class="src src-bash">
+<div class="src src-bash">
 <div class="highlight">
 <pre>
 uname -a
 </pre>
 </div>
-</pre>
+</div>
 </li>
 </ul>
 <h2 id="headline-24">
@@ -463,7 +463,7 @@ When inserting an image link like <img src="/home/amos/Pictures/Screenshots/img-
 <h3 id="headline-26">
 <a href="https://github.com/gohugoio/hugo/issues/4006">#4006</a> source code blocks in org not rendered correctly
 </h3>
-<pre class="src src-emacs-lisp">
+<div class="src src-emacs-lisp">
 <div class="highlight">
 <pre>
 (defun small-shell ()
@@ -474,7 +474,7 @@ When inserting an image link like <img src="/home/amos/Pictures/Screenshots/img-
   (ansi-term))
 </pre>
 </div>
-</pre>
+</div>
 <h1 id="headline-27">
 Footnotes
 </h1>