LibWeb: Expose type and raw values of basic CSS types

This makes it possible to do arithmetic on them without having to
resolve to their canonical unit, which often requires context
information that is not available until the last minute. For example, a
Length cannot be resolved to px without knowing the font size, parent
element's size, etc.

Only Length currently requires such context, but treating all these
types the same means that code that manipulates them does not need to
know or care if a new unit gets added that does require contextual
information.

Userland/Libraries/LibWeb/CSS/Angle.h

@@ -30,6 +30,9 @@ public:
     ErrorOr<String> to_string() const;
     float to_degrees() const;
 
+    Type type() const { return m_type; }
+    float raw_value() const { return m_value; }
+
     bool operator==(Angle const& other) const
     {
         return m_type == other.m_type && m_value == other.m_value;