Move parsing of html string to Html() constructor

Author: tneotia

lib/flutter_html.dart

@@ -92,12 +92,11 @@ class Html extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final double width = shrinkWrap ? null : MediaQuery.of(context).size.width;
-
+    final dom.Document doc = data != null ? HtmlParser.parseHTML(data) : document;
     return Container(
       width: width,
       child: HtmlParser(
-        htmlData: data,
-        userDocument: document,
+        htmlData: doc,
         onLinkTap: onLinkTap,
         onImageTap: onImageTap,
         onImageError: onImageError,

lib/html_parser.dart

@@ -25,8 +25,7 @@ typedef CustomRender = dynamic Function(
 );
 
 class HtmlParser extends StatelessWidget {
-  final String htmlData;
-  final dom.Document userDocument;
+  final dom.Document htmlData;
   final OnTap onLinkTap;
   final OnTap onImageTap;
   final ImageErrorListener onImageError;
@@ -40,7 +39,6 @@ class HtmlParser extends StatelessWidget {
 
   HtmlParser({
     @required this.htmlData,
-    @required this.userDocument,
     this.onLinkTap,
     this.onImageTap,
     this.onImageError,
@@ -54,11 +52,8 @@ class HtmlParser extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    dom.Document document;
-    if (userDocument == null) document = parseHTML(htmlData);
-    if (htmlData == null) document = userDocument;
     StyledElement lexedTree = lexDomTree(
-      document,
+      htmlData,
       customRender?.keys?.toList() ?? [],
       blacklistedElements,
       navigationDelegateForIframe,