gitweb: Allow line number toggling with Javascript

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

gitweb/gitweb.perl

@@ -4547,6 +4547,25 @@ sub git_print_page_path {
 			print $cgi->a({-href => href(action=>"blob_plain", file_name=>$file_name,
 			                             hash_base=>$hb),
 			              -title => $name}, esc_path($basename));
+			print '    
+<a id="lineNoToggle" href="#" onclick="toggleLineNumbers();"></a>
+<script>
+function toggleLineNumbers() {
+        e = document.getElementById("lineNoStyle");
+        e2 = document.getElementById("lineNoToggle");
+        if (e2.innerHTML == "[Hide line numbers]") {
+                e.innerHTML = ".linenr { display:none; }";
+                e2.innerHTML = "[Show line numbers]";
+        }
+        else {
+                e.innerHTML = "";
+                e2.innerHTML = "[Hide line numbers]";
+        }
+}
+document.getElementsByTagName("head")[0].innerHTML += "<style id=\'lineNoStyle\'></style>";
+toggleLineNumbers();
+</script>
+';
 		} elsif (defined $type && $type eq 'tree') {
 			print $cgi->a({-href => href(action=>"tree", file_name=>$file_name,
 			                             hash_base=>$hb),