inSetterContext abstract method Null safety
true if this expression is computing a left-hand value (that is,
if this expression is in a context where the operator '=' will be
Note that inGetterContext and inSetterContext are not opposites, nor
are they mutually exclusive. In other words, it is possible for both
methods to return
true when invoked on the same node.
// TODO(brianwilkerson) Convert this to a getter. bool inSetterContext();