getField method
Invokes a getter and returns a mirror on the result.
The getter can be the implicit getter for a field or a user-defined getter method.
Let o be the object reflected by this mirror,
let f be the simple name of the getter denoted by fieldName.
Then this method will perform the getter invocation o.f in a scope that has access to the private members of o (if o is a class or library) or the private members of the class of o (otherwise).
If this mirror is an InstanceMirror, and fieldName denotes an instance
method on its reflectee, the result of the invocation is an instance
mirror on a closure corresponding to that method.
If this mirror is a LibraryMirror, and fieldName denotes a top-level
method in the corresponding library, the result of the invocation is an
instance mirror on a closure corresponding to that method.
If this mirror is a ClassMirror, and fieldName denotes a static method
in the corresponding class, the result of the invocation is an instance
mirror on a closure corresponding to that method.
If the invocation returns a result r, this method returns the result of calling reflect(r).
If the invocation causes a compilation error, the effect is the same as if a non-reflective compilation error had been encountered.
If the invocation throws an exception e (that it does not catch), this method throws e.
Implementation
// TODO(ahe): Remove stuff about scope and private members. [fieldName] is a
// capability giving access to private members.
InstanceMirror getField(Symbol fieldName);