GTextEditor: Make visual lines stop after their last character

Instead of letting each visual line run to the end of the editor when
wrapping lines, stop each visual line where it runs ouf characters.

Fixes #493.

Libraries/LibGUI/GTextEditor.cpp

@@ -156,7 +156,7 @@ GTextPosition GTextEditor::text_position_at(const Point& a_position) const
         column_index = (position.x() + glyph_width() / 2) / glyph_width();
         if (is_line_wrapping_enabled()) {
             line.for_each_visual_line([&](const Rect& rect, const StringView&, int start_of_line) {
-                if (rect.contains(position)) {
+                if (rect.contains_vertically(position.y())) {
                     column_index += start_of_line;
                     return IterationDecision::Break;
                 }
@@ -405,7 +405,7 @@ void GTextEditor::paint_event(GPaintEvent& event)
 
                     int selection_right = selection_ends_on_current_visual_line
                         ? content_x_for_position({ line_index, selection_end_column_within_line })
-                        : visual_line_rect.right();
+                        : visual_line_rect.right() + 1;
 
                     Rect selection_rect {
                         selection_left,
@@ -1412,7 +1412,7 @@ void GTextEditor::Line::for_each_visual_line(Callback callback) const
         Rect visual_line_rect {
             m_visual_rect.x(),
             m_visual_rect.y() + (line_index * m_editor.line_height()),
-            m_visual_rect.width(),
+            m_editor.font().width(visual_line_view),
             m_editor.line_height()
         };
         if (callback(visual_line_rect, visual_line_view, start_of_line) == IterationDecision::Break)