HTML reader: parse inline style elements as RawInline.

This is a cleaner fix to #10643 than the reverted commit 7fe8c92.

Styles are not stripped, but with this change they will not
interfere with inline parsing.

Closes #11246.

test/command/10643.md

@@ -0,0 +1,11 @@
+```
+% pandoc -f html -t native
+<p>A<style></style>B</p>
+^D
+[ Para
+    [ Str "A"
+    , RawInline (Format "html") "<style></style>"
+    , Str "B"
+    ]
+]
+```