WebImage constructor Null safety

1. flutter_cast_framework
2. cast
3. WebImage
4. WebImage constructor

WebImage class

1. Constructors
2. WebImage
3. Properties
4. hashCode
5. runtimeType
6. url
7. Methods
8. encode
9. noSuchMethod
10. toString
11. Operators
12. operator ==
13. Static methods
14. decode