monoblue: make actual changeset entries have backgrounds on /graph

This patch removes a separate container for backgrounds only and puts
backgrounds on changeset elements themselves. This makes it so that JS code
doesn't need to create background elements separately anymore.

There's a bit of manipulating positions of elements: every changeset entry has
a "fg" element that gets a higher z-index than <canvas> element. This
prioritizes text information, so that even if it somehow gets close to the
graph drawn on <canvas> (which has z-index of 5), it'll still be on top of it.
This can happen if commit message has a long first line and browser window is
narrow, for example.

'parity' is added to each entry because there's no stripes2 class in monoblue,
only in paper.

mercurial/hgweb/webcommands.py

@@ -1265,6 +1265,7 b' def graph(web, req, tmpl):'
                 for (id, type, ctx, vtx, edges) in fulltree()]
 
     def nodes():
+        parity = paritygen(web.stripecount)
         for row, (id, type, ctx, vtx, edges) in enumerate(tree):
             entry = webutil.commonentry(web.repo, ctx)
             edgedata = [{'col': edge[0],
@@ -1276,6 +1277,7 b' def graph(web, req, tmpl):'
 
             entry.update({'col': vtx[0],
                           'color': (vtx[1] - 1) % 6 + 1,
+                          'parity': next(parity),
                           'edges': edgedata,
                           'row': row,
                           'nextrow': row + 1})

mercurial/templates/monoblue/graph.tmpl

@@ -29,7 +29,6 b''
 
     <div id="noscript">The revision graph only works with JavaScript-enabled browsers.</div>
     <div id="wrapper">
-        <ul id="nodebgs"></ul>
         <canvas id="graph"></canvas>
         <ul id="graphnodes">{nodes%graphentry}</ul>
     </div>
@@ -40,12 +39,6 b''
     var data = {jsdata|json};
     var graph = new Graph();
     graph.scale({bg_height});
-
-    graph.vertex = function(x, y, radius, color, parity, cur) \{
-        Graph.prototype.vertex.apply(this, arguments);
-        return ['<li class="bg parity' + parity + '"></li>', ''];
-    }
-
     graph.render(data);
     </script>
 

mercurial/templates/monoblue/graphentry.tmpl

@@ -1,7 +1,9 b''
-<li data-node="{node|short}">
+<li class="parity{parity}" data-node="{node|short}">
+    <div class="fg">
     <span class="desc">
         <a href="{url|urlescape}rev/{node|short}{sessionvars%urlparameter}">{desc|strip|firstline|escape|nonempty}</a>
     </span>
     {alltags}
     <div class="info"><span class="age">{date|rfc822date}</span>, by {author|person}</div>
+    </div>
 </li>

mercurial/templates/static/style-monoblue.css

@@ -478,27 +478,29 b' canvas {'
 	top: -0.7em;
 }
 
-ul#nodebgs li.parity0 {
+ul#graphnodes li.parity0 {
     background: #F1F6F7;
 }
 
-ul#nodebgs li.parity1 {
+ul#graphnodes li.parity1 {
     background: #FFFFFF;
 }
 
 ul#graphnodes {
-	position: absolute;
-	z-index: 10;
-	top: 7px;
 	list-style: none inside none;
+	margin: 0;
+	padding: 0;
 }
 
-ul#nodebgs {
-	list-style: none inside none;
+ul#graphnodes li {
+	height: 37px;
+	overflow: visible;
+	padding-top: 2px;
 }
 
-ul#graphnodes li, ul#nodebgs li {
-	height: 39px;
+ul#graphnodes li .fg {
+	position: absolute;
+	z-index: 10;
 }
 
 ul#graphnodes li .info {