Update inspectNode implementation (emberjs#1105)

A while ago we discovered the reason this dance was needed, so we
documented the reason and simplified the implementation a little
bit while we are at it.

app/adapters/web-extension.js

@@ -80,10 +80,13 @@ export default BasicAdapter.extend({
    * Open the devtools "Elements" tab and select a specific DOM node.
    *
    * @method inspectDOMNode
-   * @param  {String} selector XPath selector
+   * @param {String} name
    */
-  inspectDOMNode(selector) {
-    chrome.devtools.inspectedWindow.eval(`inspect($x('${selector}')[0])`);
+  inspectDOMNode(name) {
+    chrome.devtools.inspectedWindow.eval(`
+      inspect(window[${JSON.stringify(name)}]);
+      delete window[${JSON.stringify(name)}];
+    `);
   },
 
   /**

app/routes/component-tree.js

@@ -58,8 +58,8 @@ export default TabRoute.extend({
     this.set('controller.inspectingViews', false);
   },
 
-  inspectDOMNode({ selector }) {
-    this.get('port.adapter').inspectDOMNode(selector);
+  inspectDOMNode({ name }) {
+    this.port.adapter.inspectDOMNode(name);
   },
 
   actions: {

ember_debug/adapters/basic.js

@@ -60,17 +60,17 @@ export default EmberObject.extend({
   },
 
   /**
-    Inspect a specific element.  This usually
+    Inspect a specific DOM node. This usually
     means using the current environment's tools
-    to inspect the element in the DOM.
+    to inspect the node in the DOM.
 
-    For example, in chrome, `inspect(elem)`
+    For example, in chrome, `inspect(node)`
     will open the Elements tab in dev tools
-    and highlight the element.
+    and highlight the DOM node.
 
-    @param {DOM Element} elem
+    @param {Node} node
   */
-  inspectElement(/* elem */) {},
+  inspectNode(/* node */) {},
 
   _messageReceived(message) {
     this._messageCallbacks.forEach(callback => {

ember_debug/adapters/web-extension.js

@@ -32,24 +32,35 @@ export default BasicAdapter.extend({
   },
 
   /**
-   * Open the devtools "Elements" and select an element.
+   * Open the devtools "Elements" and select an DOM node.
    *
-   * NOTE:
-   * This method was supposed to call `inspect` which is a Chrome specific function
-   * that can either be called from the console or from code evaled using `inspectedWindow.eval`
-   * (which is how this code is executed). See https://developer.chrome.com/extensions/devtools#evaluating-js.
-   * However for some reason Chrome 52+ has started throwing an Error that `inspect`
-   * is not a function when called from this code. The current workaround is to
-   * message the Ember Ibspector asking it to execute `inspected.Window.eval('inspect(element)')`
-   * for us.
-   *
-   * @param  {HTMLElement} elem The element to select
+   * @param  {Node} node The DOM node to select
    */
-  inspectElement(elem) {
-    /* inspect(elem); */
-    this.get('namespace.port').send('view:inspectDOMNode', {
-      selector: `//*[@id="${elem.getAttribute('id')}"]`
-    });
+  inspectNode(node) {
+    // NOTE:
+    //
+    // Basically, we are just trying to call `inspect(node)` here.
+    // However, `inspect` is a special function that is in the global
+    // scope but not on the global object (i.e. `window.inspect`) does
+    // not work. This sometimes causes problems, because, e.g. if the
+    // page has a div with the ID `inspect`, `window.inspect` will point
+    // to that div and shadown the "global" inspect function with no way
+    // to get it back. That causes "`inspect` is not a function" errors.
+    //
+    // As it turns out, however, when the extension page evals, the
+    // `inspect` function does not get shadowed. So, we can ask the
+    // inspector extension page to call that function for us, using
+    // `inspected.Window.eval('inspect(node)')`.
+    //
+    // However, since we cannot just send the DOM node directly to the
+    // extension, we will have to store it in a temporary global variable
+    // so that the extension can find it.
+
+    let name = `__EMBER_INSPECTOR_${(Math.random() * 100000000).toFixed(0)}`;
+
+    window[name] = node;
+
+    this.get('namespace.port').send('view:inspectDOMNode', { name });
   },
 
   _listen() {

ember_debug/view-debug.js

@@ -168,7 +168,7 @@ export default EmberObject.extend(PortMixin, {
    * @param  {Element} element The element to inspect
    */
   inspectElement(element) {
-    this.get('adapter').inspectElement(element);
+    this.get('adapter').inspectNode(element);
   },
 
   sendTree() {