Track whitespace left on blank lines to match CommonMark

Test changes copy pasted to match CommonMark reference parser

tests/data/code_block.html

@@ -1,20 +1,24 @@
 <pre><code>&lt;?php
 
 $message = 'Hello World!';
-echo $message;</code></pre>
+echo $message;
+</code></pre>
 <hr />
 <pre><code>&gt; not a quote
 - not a list item
-[not a reference]: http://foo.com</code></pre>
+[not a reference]: http://foo.com
+</code></pre>
 <hr />
 <pre><code>foo
 
 
-bar</code></pre>
+bar
+</code></pre>
 <hr />
 <ul>
 <li>
 <p>foo</p>
-<pre><code>  bar</code></pre>
+<pre><code>  bar
+</code></pre>
 </li>
 </ul>

tests/data/escaping.html

@@ -1,6 +1,7 @@
 <p>escaped *emphasis*.</p>
 <p><code>escaped \*emphasis\* in a code span</code></p>
-<pre><code>escaped \*emphasis\* in a code block</code></pre>
+<pre><code>escaped \*emphasis\* in a code block
+</code></pre>
 <p>\ ` * _ { } [ ] ( ) &gt; # + - . !</p>
 <p><em>one_two</em> <strong>one_two</strong></p>
 <p><em>one*two</em> <strong>one*two</strong></p>

tests/data/fenced_code_block.html

@@ -1,18 +1,25 @@
 <pre><code>&lt;?php
 
 $message = 'fenced code block';
-echo $message;</code></pre>
-<pre><code>tilde</code></pre>
-<pre><code class="language-php">echo 'language identifier';</code></pre>
-<pre><code class="language-c#">echo 'language identifier with non words';</code></pre>
+echo $message;
+</code></pre>
+<pre><code>tilde
+</code></pre>
+<pre><code class="language-php">echo 'language identifier';
+</code></pre>
+<pre><code class="language-c#">echo 'language identifier with non words';
+</code></pre>
 <pre><code class="language-html+php">&lt;?php
 echo &quot;Hello World&quot;;
 ?&gt;
-&lt;a href=&quot;http://auraphp.com&quot; &gt;Aura Project&lt;/a&gt;</code></pre>
+&lt;a href=&quot;http://auraphp.com&quot; &gt;Aura Project&lt;/a&gt;
+</code></pre>
 <pre><code>the following isn't quite enough to close
 ```
-still a fenced code block</code></pre>
+still a fenced code block
+</code></pre>
 <pre><code>foo
 
 
-bar</code></pre>
+bar
+</code></pre>

tests/data/tab-indented_code_block.html

@@ -3,4 +3,5 @@
 $message = 'Hello World!';
 echo $message;
 
-echo &quot;following a blank line&quot;;</code></pre>
+echo &quot;following a blank line&quot;;
+</code></pre>

tests/data/whitespace.html

@@ -1 +1,2 @@
-<pre><code>code</code></pre>
+<pre><code>code
+</code></pre>