LibWeb: Simplify text chunk iteration a little bit

Instead of TextNode::ChunkIterator having two bool members to remember
things across calls to next(), this patch reorganizes the loop in next()
so that preserved newline/whitespace chunks are emitted right away
instead of in an awkward deferred way.

Userland/Libraries/LibWeb/Layout/TextNode.h

@@ -42,8 +42,6 @@ public:
         const LayoutMode m_layout_mode;
         const bool m_wrap_lines;
         const bool m_respect_linebreaks;
-        bool m_last_was_space { false };
-        bool m_last_was_newline { false };
         Utf8View m_utf8_view;
         Utf8View::Iterator m_iterator;
     };