rss_converter_twitter.com.xsl: explain why the style attribute is removed

Since commit 6817108 (rss_converter_twitter.com.xsl: strip the style
attribute from HTML elements, 2017-06-08) the twitter.com stylesheet
removes the "style" attribute from elements when copying them.

This is in order to create a more visually neutral output, but also
because the style attribute may even contain dangerous content:
https://validator.w3.org/feed/docs/warning/DangerousStyleAttr.html

However someone who reads the code may not be familiar with (or have
forgotten) why this is done, so explain that in a comment to avoid them
the burden of digging in the project history.

diff --git a/src/rss_converter_twitter.com.xsl b/src/rss_converter_twitter.com.xsl
index 2cf1868..06ae70a 100644 (file)
--- a/src/rss_converter_twitter.com.xsl
+++ b/src/rss_converter_twitter.com.xsl
@@ -35,6 +35,11 @@
     <!-- Identity transform -->
     <xsl:template match="@*|node()">
         <xsl:copy>
     <!-- Identity transform -->
     <xsl:template match="@*|node()">
         <xsl:copy>

+            <!--
+                Strip the style attribute while copying elements because it may be
+                dangerous, see:
+                https://validator.w3.org/feed/docs/warning/DangerousStyleAttr.html
+            -->

             <xsl:apply-templates select="@*[not(name() = 'style')]|node()"/>
         </xsl:copy>
     </xsl:template>
             <xsl:apply-templates select="@*[not(name() = 'style')]|node()"/>
         </xsl:copy>
     </xsl:template>