LibWeb: Remove StyleValue::has_rect()

This behaves identically to `is_rect()`

Userland/Libraries/LibWeb/CSS/StyleProperties.cpp

@@ -357,7 +357,7 @@ Optional<CSS::ImageRendering> StyleProperties::image_rendering() const
 CSS::Clip StyleProperties::clip() const
 {
     auto value = property(CSS::PropertyID::Clip);
-    if (!value->has_rect())
+    if (!value->is_rect())
         return CSS::Clip::make_auto();
     return CSS::Clip(value->as_rect().rect());
 }

Userland/Libraries/LibWeb/CSS/StyleValue.h

@@ -294,7 +294,6 @@ public:
     bool has_auto() const;
     virtual bool has_color() const { return false; }
     virtual bool has_length() const { return false; }
-    virtual bool has_rect() const { return false; }
     virtual bool has_number() const { return false; }
     virtual bool has_integer() const { return false; }
 

Userland/Libraries/LibWeb/CSS/StyleValues/RectStyleValue.h

@@ -21,7 +21,6 @@ public:
 
     EdgeRect rect() const { return m_rect; }
     virtual ErrorOr<String> to_string() const override;
-    virtual bool has_rect() const override { return true; }
 
     bool properties_equal(RectStyleValue const& other) const { return m_rect == other.m_rect; }