fix: Throw DOMException when calling removeChild with invalid paramet…

…er (#494)

BREAKING CHANGE: Previously it was possible (but not documented) to call
`Node.removeChild` with any node in the tree,
and with certain exceptions, it would work. This is no longer the case:
calling `Node.removeChild` with an argument that is not a direct child
of the node that it is called from, will throw a NotFoundError
DOMException, as it is described by the specs.

https://dom.spec.whatwg.org/#concept-node-pre-remove 
Fixes #135

lib/dom.js

@@ -952,22 +952,26 @@ function _onUpdateChild(doc, el, newChild) {
  * @private
  */
 function _removeChild(parentNode, child) {
-	var previous = child.previousSibling;
-	var next = child.nextSibling;
-	if (previous) {
-		previous.nextSibling = next;
+	if (parentNode !== child.parentNode) {
+		throw new DOMException(NOT_FOUND_ERR, "child's parent is not parent");
+	}
+	//var index = parentNode.childNodes.
+	var oldPreviousSibling = child.previousSibling;
+	var oldNextSibling = child.nextSibling;
+	if (oldPreviousSibling) {
+		oldPreviousSibling.nextSibling = oldNextSibling;
 	} else {
-		parentNode.firstChild = next;
+		parentNode.firstChild = oldNextSibling;
 	}
-	if (next) {
-		next.previousSibling = previous;
+	if (oldNextSibling) {
+		oldNextSibling.previousSibling = oldPreviousSibling;
 	} else {
-		parentNode.lastChild = previous;
+		parentNode.lastChild = oldPreviousSibling;
 	}
+	_onUpdateChild(parentNode.ownerDocument, parentNode);
 	child.parentNode = null;
 	child.previousSibling = null;
 	child.nextSibling = null;
-	_onUpdateChild(parentNode.ownerDocument, parentNode);
 	return child;
 }
 
@@ -1345,10 +1349,11 @@ Document.prototype = {
 		return newChild;
 	},
 	removeChild: function (oldChild) {
-		if (this.documentElement == oldChild) {
+		var removed = _removeChild(this, oldChild);
+		if (removed === this.documentElement) {
 			this.documentElement = null;
 		}
-		return _removeChild(this, oldChild);
+		return removed;
 	},
 	replaceChild: function (newChild, oldChild) {
 		//raises

test/dom/document.test.js

@@ -379,8 +379,21 @@ describe('Document.prototype', () => {
 			// expect(doc.documentElement).toBeNull();
 			expect(initialElement.parentNode).toBeNull();
 			expect(initialElement.nextSibling).toBeNull();
-			// expect(initialElement.previousSibling).toBeNull();
+			expect(initialElement.previousSibling).toBeNull();
 			expect(doc.childNodes).toHaveLength(1);
 		});
+
+		it('Remove child from non-parent node throws', async () => {
+			const ISSUE_CHECK = `<xml>
+				<a><x/></a>
+				<b><y/></b>
+			</xml>`;
+			const dom = new DOMParser().parseFromString(ISSUE_CHECK);
+			const ys = dom.getElementsByTagName('y');
+			const as = dom.getElementsByTagName('a');
+
+			expect(() => as[0].removeChild(ys[0])).toThrow(DOMException);
+			expect(dom.toString()).toBe(ISSUE_CHECK);
+		});
 	});
 });