Handle HTML 'ol' start attribute in shr.el

* lisp/net/shr.el (shr-tag-ol): Don't automatically assume
1-indexing for all ordered lists, use <ol> if given.

* etc/NEWS: Announce change in shr behavior.

* test/data/shr/ol.html:
* test/data/shr/ol.txt: New test data files.

2 files changed, 48 insertions, 0 deletions

diff --git a/test/data/shr/ol.html b/test/data/shr/ol.html
new file mode 100644
index 00000000000..f9a15f26409
--- /dev/null
+++ b/test/data/shr/ol.html
@@ -0,0 +1,29 @@
+<ol>
+  <li>one</li>
+  <li>two</li>
+  <li>three</li>
+</ol>
+
+<ol start="10">
+  <li>ten</li>
+  <li>eleven</li>
+  <li>twelve</li>
+</ol>
+
+<ol start="0">
+  <li>zero</li>
+  <li>one</li>
+  <li>two</li>
+</ol>
+
+<ol start="-5">
+  <li>minus five</li>
+  <li>minus four</li>
+  <li>minus three</li>
+</ol>
+
+<ol start="notanumber">
+  <li>one</li>
+  <li>two</li>
+  <li>three</li>
+</ol>
diff --git a/test/data/shr/ol.txt b/test/data/shr/ol.txt
new file mode 100644
index 00000000000..0d46e2a8ddb
--- /dev/null
+++ b/test/data/shr/ol.txt
@@ -0,0 +1,19 @@
+1 one
+2 two
+3 three
+
+10 ten
+11 eleven
+12 twelve
+
+0 zero
+1 one
+2 two
+
+-5 minus five
+-4 minus four
+-3 minus three
+
+1 one
+2 two
+3 three