- Make sure to send the subdirectory when restarting a build

- Make sure to use the subdirectory to read the Dockerfile's location in a build package, and display the path
- Nicer UI for showing the trigger description in the build view
- Fix an NPE in the file change tree

static/js/graphing.js

@@ -851,7 +851,8 @@ function FileTreeBase() {
  * Calculates the dimensions of the tree.
  */
 FileTreeBase.prototype.calculateDimensions_ = function(container) {
-  var cw = document.getElementById(container).clientWidth;
+  var containerElm = document.getElementById(container);
+  var cw = containerElm ? containerElm.clientWidth : 1200;
   var barHeight = 20;
   var ch = (this.getNodesHeight() * barHeight) + 40;