Create graph elements for each key in a keyed histogram.

Regression. Used to work, but would show _all_ keys. With keyLimit, I expect
this to be more often used.

wrapper/telemetry-wrapper.js

@@ -24,19 +24,6 @@ window.TelemetryWrapper.go = function (params, element) {
   Telemetry.init(function () {
     setDefaultParams(params);
 
-    var graphContainerEl = document.createElement('div');
-    graphContainerEl.className = 'graph-container';
-    var graphTitleEl = document.createElement('h2');
-    graphTitleEl.className = 'graph-title';
-    graphContainerEl.appendChild(graphTitleEl);
-    var graphEl = document.createElement('div');
-    graphEl.className = 'graph';
-    var graphLegendEl = document.createElement('div');
-    graphLegendEl.className = 'graph-legend';
-    graphEl.appendChild(graphLegendEl);
-    graphContainerEl.appendChild(graphEl);
-    element.appendChild(graphContainerEl);
-
     var evolutionsPromise;
     if (params.evoVersions > 0) {
       // if we're composing an evolution over many versions, we need to mux over the versions
@@ -168,6 +155,20 @@ window.TelemetryWrapper.go = function (params, element) {
             .filter(evo => !!evo);
         }
 
+        // Construct the graph elements and add them to `element`
+        var graphContainerEl = document.createElement('div');
+        graphContainerEl.className = 'graph-container';
+        var graphTitleEl = document.createElement('h2');
+        graphTitleEl.className = 'graph-title';
+        graphContainerEl.appendChild(graphTitleEl);
+        var graphEl = document.createElement('div');
+        graphEl.className = 'graph';
+        var graphLegendEl = document.createElement('div');
+        graphLegendEl.className = 'graph-legend';
+        graphEl.appendChild(graphLegendEl);
+        graphContainerEl.appendChild(graphEl);
+        element.appendChild(graphContainerEl);
+
         // Describe the graph, briefly
         var graphTitle = evolutions[0].measure;
         if (key) {