mshtml: Implement previousElementSibling for Elements.

dlls/mshtml/htmlelem.c

@@ -6553,8 +6553,30 @@ static HRESULT WINAPI ElementTraversal_get_lastElementChild(IElementTraversal *i
 static HRESULT WINAPI ElementTraversal_get_previousElementSibling(IElementTraversal *iface, IHTMLElement **p)
 {
     HTMLElement *This = impl_from_IElementTraversal(iface);
-    FIXME("(%p)->(%p)\n", This, p);
-    return E_NOTIMPL;
+    nsIDOMElement *nselem = NULL;
+    HTMLElement *elem;
+    HRESULT hres;
+
+    TRACE("(%p)->(%p)\n", This, p);
+
+    if(!This->dom_element) {
+        *p = NULL;
+        return S_OK;
+    }
+
+    nsIDOMElement_GetPreviousElementSibling(This->dom_element, &nselem);
+    if(!nselem) {
+        *p = NULL;
+        return S_OK;
+    }
+
+    hres = get_element(nselem, &elem);
+    nsIDOMElement_Release(nselem);
+    if(FAILED(hres))
+        return hres;
+
+    *p = &elem->IHTMLElement_iface;
+    return S_OK;
 }
 
 static HRESULT WINAPI ElementTraversal_get_nextElementSibling(IElementTraversal *iface, IHTMLElement **p)

dlls/mshtml/tests/dom.js

@@ -98,6 +98,10 @@ sync_test("ElementTraversal", function() {
             "div.firstElementChild.nextElementSibling.outerHTML = " + div.firstElementChild.nextElementSibling.outerHTML);
     ok(div.lastElementChild.nextElementSibling === null,
             "div.lastElementChild.nextElementSibling = " + div.lastElementChild.nextElementSibling);
+    ok(div.lastElementChild.previousElementSibling.outerHTML === "<script>/* */</script>",
+            "div.lastElementChild.previousElementSibling.outerHTML = " + div.lastElementChild.previousElementSibling.outerHTML);
+    ok(div.firstElementChild.previousElementSibling === null,
+            "div.firstElementChild.previousElementSibling = " + div.firstElementChild.previousElementSibling);
 
     div.innerHTML = "abc";
     ok(div.firstElementChild === null, "div.firstElementChild = " + div.firstElementChild);