FunctionTypeMacro constructor Null safety

1. macro_builder
2. definition
3. FunctionTypeMacro
4. FunctionTypeMacro constructor

FunctionTypeMacro class

1. Constructors
2. FunctionTypeMacro
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. visitFunctionType
10. Operators
11. operator ==