Eliminate type anotations on intialising formals (#514)
Eliminate type anotations on intialising formals (#514)

For `this.foo` initialising formals in constructors, type annotations
are redundant with the field declarations.
cbracken/quiver-dart,google/quiver-dart,cbracken/quiver-dart,kevmoo/quiver-dart,kevmoo/quiver-dart