Bug 1409040 - Add element.isElement shorthand. r=maja_zf

Introduces new element.isElement shorthand API for identifying DOM-,
SVG-, and XUL elements.

It is the equivalent of this:

	if (element.isDOMElement(el) ||
	    element.isSVGElement(el) ||
	    element.isXULElement(el)) {
	  // ...
	}

MozReview-Commit-ID: H8MDkP5bQmW

--HG--
extra : rebase_source : 6bef09999e47b178614e4bd307266b4449f39901

testing/marionette/element.js

@@ -1049,6 +1049,22 @@ element.scrollIntoView = function(el) {
   }
 };
 
+/**
+ * Ascertains whether <var>node</var> is a DOM-, SVG-, or XUL element.
+ *
+ * @param {*} node
+ *     Element thought to be an <code>Element</code>,
+ *     <code>SVGElement</code>, or <code>XULElement</code>.
+ *
+ * @return {boolean}
+ *     True if <var>node</var> is an element, false otherwise.
+ */
+element.isElement = function(node) {
+  return element.isDOMElement(node) ||
+      element.isSVGElement(node) ||
+      element.isXULElement(node);
+};
+
 /**
  * Ascertains whether <var>node</var> is a DOM element.
  *

testing/marionette/evaluate.js

@@ -269,8 +269,8 @@ evaluate.toJSON = function(obj, seenEls) {
   } else if (element.isCollection(obj)) {
     return [...obj].map(el => evaluate.toJSON(el, seenEls));
 
-  // HTMLElement
-  } else if ("nodeType" in obj && obj.nodeType == obj.ELEMENT_NODE) {
+  // Element, SVGElement, XULElement
+  } else if (element.isElement(obj)) {
     let uuid = seenEls.add(obj);
     return element.makeWebElement(uuid);
 

testing/marionette/test_element.js

@@ -115,6 +115,19 @@ add_test(function test_isSelected() {
   run_next_test();
 });
 
+add_test(function test_isElement() {
+  ok(element.isElement(domEl));
+  ok(element.isElement(svgEl));
+  ok(element.isElement(xulEl));
+  ok(!element.isElement(domWin));
+  ok(!element.isElement(domFrame));
+  for (let typ of [true, 42, {}, [], undefined, null]) {
+    ok(!element.isElement(typ));
+  }
+
+  run_next_test();
+});
+
 add_test(function test_isDOMElement() {
   ok(element.isDOMElement(domEl));
   ok(!element.isDOMElement(svgEl));