LibWeb: Rename is_scrollable() to is_user_scrollable()

is_user_scrollable() is more appropriate name since this function
returns true only for boxes scrollable by user interaction.

Userland/Libraries/LibWeb/Layout/Box.cpp

@@ -55,7 +55,7 @@ bool Box::is_scroll_container() const
         || overflow_value_makes_box_a_scroll_container(computed_values().overflow_y());
 }
 
-bool Box::is_scrollable() const
+bool Box::is_user_scrollable() const
 {
     // FIXME: Support horizontal scroll as well (overflow-x)
     return computed_values().overflow_y() == CSS::Overflow::Scroll || computed_values().overflow_y() == CSS::Overflow::Auto;

Userland/Libraries/LibWeb/Layout/Box.h

@@ -54,7 +54,7 @@ public:
 
     bool is_scroll_container() const;
 
-    bool is_scrollable() const;
+    bool is_user_scrollable() const;
 
 protected:
     Box(DOM::Document&, DOM::Node*, NonnullRefPtr<CSS::StyleProperties>);

Userland/Libraries/LibWeb/Page/EventHandler.cpp

@@ -165,7 +165,7 @@ bool EventHandler::handle_mousewheel(CSSPixelPoint position, unsigned button, un
 
     auto* containing_block = paintable->containing_block();
     while (containing_block) {
-        if (containing_block->is_scrollable()) {
+        if (containing_block->is_user_scrollable()) {
             const_cast<Painting::PaintableBox*>(containing_block->paintable_box())->handle_mousewheel({}, position, buttons, modifiers, wheel_delta_x * scroll_step_size, wheel_delta_y * scroll_step_size);
             break;
         }

Userland/Libraries/LibWeb/Painting/PaintableBox.cpp

@@ -729,7 +729,7 @@ void PaintableWithLines::paint(PaintContext& context, PaintPhase phase) const
 
 bool PaintableBox::handle_mousewheel(Badge<EventHandler>, CSSPixelPoint, unsigned, unsigned, int wheel_delta_x, int wheel_delta_y)
 {
-    if (!layout_box().is_scrollable())
+    if (!layout_box().is_user_scrollable())
         return false;
     scroll_by(wheel_delta_x, wheel_delta_y);
     return true;