diff -r 000000000000 -r 6474c204b198 browser/devtools/inspector/test/browser_inspector_invalidate.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/inspector/test/browser_inspector_invalidate.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,51 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+function test() {
+  let doc;
+  let div;
+  let inspector;
+
+  function createDocument() {
+    div = doc.createElement("div");
+    div.setAttribute("style", "width: 100px; height: 100px; background:yellow;");
+    doc.body.appendChild(div);
+
+    openInspector(aInspector => {
+      inspector = aInspector;
+      inspector.toolbox.highlighter.showBoxModel(getNodeFront(div)).then(runTest);
+    });
+  }
+
+  function runTest() {
+    let rect = getSimpleBorderRect();
+    is(rect.width, 100, "outline has the right width");
+
+    div.style.width = "200px";
+    inspector.toolbox.once("highlighter-ready", testRectWidth);
+  }
+
+  function testRectWidth() {
+    let rect = getSimpleBorderRect();
+    is(rect.width, 200, "outline updated");
+    finishUp();
+  }
+
+  function finishUp() {
+    inspector.toolbox.highlighter.hideBoxModel().then(() => {
+      doc = div = inspector = null;
+      gBrowser.removeCurrentTab();
+      finish();
+    });
+  }
+
+  waitForExplicitFinish();
+  gBrowser.selectedTab = gBrowser.addTab();
+  gBrowser.selectedBrowser.addEventListener("load", function() {
+    gBrowser.selectedBrowser.removeEventListener("load", arguments.callee, true);
+    doc = content.document;
+    waitForFocus(createDocument, content);
+  }, true);
+
+  content.location = "data:text/html;charset=utf-8,browser_inspector_invalidate.js";
+}