go.tools/godoc: fix two regressions caused by -analysis CL.

- Add missing methodset.html template file.
- Suppress initial display of package callgraph.
  Client-side JS will make it visible if there is data.

LGTM=bgarcia
R=crawshaw, bgarcia
CC=golang-codereviews
https://golang.org/cl/81550043

godoc/static/godocs.js

@@ -448,6 +448,8 @@ function setupCallgraphs() {
   if (document.CALLGRAPH == null) {
     return
   }
+  document.getElementById("pkg-callgraph").style.display = "block";
+
   var treeviews = document.getElementsByClassName("treeview");
   for (var i in treeviews) {
     var tree = treeviews[i];

godoc/static/methodset.html

@@ -0,0 +1,9 @@
+<div class="toggle" style="display: none">
+	<div class="collapsed">
+		<p class="exampleHeading toggleButton">▹ <span class="text">Method set</span></p>
+	</div>
+	<div class="expanded">
+		<p class="exampleHeading toggleButton">▾ <span class="text">Method set</span></p>
+                <div style="margin-left: 1in" id='methodset-{{.Index}}'>...</div>
+	</div>
+</div>

godoc/static/package.html

@@ -111,7 +111,7 @@
 		</div><!-- .expanded -->
 		</div><!-- #pkg-index -->
 
-		<div id="pkg-callgraph" class="toggle">
+		<div id="pkg-callgraph" class="toggle" style="display: none">
 		<div class="collapsed">
 			<h2 class="toggleButton" title="Click to show Internal Call Graph section">Internal call graph ▹</h2>
 		</div> <!-- .expanded -->