HTML reader: Fix handling of invalidly nested sublists.

This revises the fix to #8150 (and the test case) and closes #9187.

HTML in the (invalid) form:

    <ul>
      <li>L1</li>
      <ul>
        <li>L1.1</li>
      </ul>
    </ul>

is treated by browsers like

    <ul>
      <li>L1
        <ul>
          <li>L1.1</li>
        </ul>
      </li>
    </ul>

not

    <ul>
      <li>L1
      <li><ul>
          <li>L1.1</li>
        </ul>
      </li>
    </ul>

as pandoc previously assumed.

This change will give a similar treatment to

    <ul>
      <li>L1</li>
      <p>foobar</p>
    </ul>

which also seems to match browser behavior.

1 files changed, 3 insertions, 3 deletions

diff --git a/test/command/8150.md b/test/command/8150.md
index c27a7abd1..5034bed1e 100644
--- a/test/command/8150.md
+++ b/test/command/8150.md
@@ -13,7 +13,7 @@ Nested bullet lists
 ^D
 -   L1
 -   L2
--   -   L3.1
+    -   L3.1
     -   L3.2
 -   L4
 ```
@@ -32,7 +32,7 @@ Nested ordered lists
 ^D
 1.  L1
 2.  L2
-3.  1.  L3.1
+    1.  L3.1
     2.  L3.2
 ```
 
@@ -50,6 +50,6 @@ Ordered list nested below an unordered list
 ^D
 -   L1
 -   L2
--   1.  L3.1
+    1.  L3.1
     2.  L3.2
 ```