Add support for inserting a Document Fragment

Previous implementation would just insert the fragment as a child node, whereas it should insert its
child nodes.

HTMLKitTests/HTMLKitMutationAlgorithmsTests.m

@@ -8,6 +8,9 @@
 
 #import <XCTest/XCTest.h>
 #import "HTMLNodes.h"
+#import "NSString+HTMLKit.h"
+
+extern uint64_t dispatch_benchmark(size_t count, void (^block)(void));
 
 @interface HTMLKitMutationAlgorithmsTests : XCTestCase
 
@@ -15,6 +18,30 @@
 
 @implementation HTMLKitMutationAlgorithmsTests
 
+- (void)testAppendDocumentFragment
+{
+	HTMLElement *element = [[HTMLElement alloc] initWithTagName:@"div"];
+	HTMLComment *comment = [HTMLComment new];
+	[element appendNode:comment];
+
+	HTMLDocumentFragment *fragment = [HTMLDocumentFragment new];
+	HTMLElement *firstChild = [HTMLElement new];
+	HTMLElement *secondChild = [HTMLElement new];
+	[fragment appendNode:firstChild];
+	[fragment appendNode:secondChild];
+
+	[element appendNode:fragment];
+	XCTAssertEqual(element.childNodesCount, 3);
+	XCTAssertEqual(fragment.childNodesCount, 0);
+
+	XCTAssertEqualObjects(firstChild.parentNode, element);
+	XCTAssertEqualObjects(secondChild.parentNode, element);
+	XCTAssertEqualObjects(element.firstChiledNode, comment);
+	XCTAssertEqualObjects(element.firstChiledNode.nextSibling, firstChild);
+	XCTAssertEqualObjects(element.lastChildNode.previousSibling, firstChild);
+	XCTAssertEqualObjects(element.lastChildNode, secondChild);
+}
+
 - (void)testValidParentNodeWhenAppending
 {
 	HTMLElement *element = [[HTMLElement alloc] initWithTagName:@"div"];