fix(Dirty Checking): fix watching methods/closures

-  BUG: DynamicFieldGetterFactory::isMethod did not handle methods
   defined in superclasses.
-  BUG: Upon detecting a method, the code assumed that you would only
   invoke it.  This broke application code that watched a method (e.g.
   by way of Component mapping) just to get the closurized value and
   store it somewhere to invoke later (test case and stack trace at end
   of this commit message.)
-  BUG: StaticFieldGetterFactory::method() and
   DynamicFieldGetterFactory::method() differed.  There was no
   difference between StaticFieldGetterFactory::method() and
   StaticFieldGetterFactory::getter(). 
   DynamicFieldGetterFactory::method(), as mentioned before, assumed
   that the only thing you could do with it was to invoke it (i.e. not a
   leaf watch.)
-  There was very little testing for StaticFieldGetterFactory.  This
   meant that, though it was out of sync with DynamicFieldGetterFactory,
   no tests were failing.

Changes in this commit:

- run the same tests against StaticFieldGetterFactory that are run
  against DynamicFieldGetterFactory
- do not call the result of GetterFactory.method()
  in "set object(value)"
- reduce the difference between the two different factories. 
  GetterFactory now only has one method in it's interface definition -
  the getter function.  `_MODE_METHOD_INVOKE_`, `isMethod`,
  `isMethodInvoke`, etc. are gone.

**Bug Details:**

Refer to the repro case at
https://github.com/chirayuk/angular.dart/compare/issue_999%5E...issue_999

```dart
// Given this object.
class Foo {
  bar(x) => x+1;
}

// This test case (in an appropriate file like `scope_spec.dart`) fails
// with a traceback

it('should watch closures', (RootScope rootScope, Logger log) {
  rootScope.context['foo'] = new Foo();
  rootScope.context['func'] = null;
  rootScope.watch('foo.bar', (v, _) { rootScope.context['func'] = v; });
  rootScope.watch('func(1)', (v, o) => log([v, o]));
  rootScope.apply();
  expect(log).toEqual([[null, null], [2, null]]);
});
```

**Stack Trace:**

    Chrome 34.0.1847 (Mac OS X 10.9.2) scope watch/digest should watch closures FAILED
    Test failed: Caught Closure call with mismatched arguments: function 'DynamicFieldGetterFactory.method.<anonymous closure>'

    NoSuchMethodError: incorrect number of arguments passed to method named 'DynamicFieldGetterFactory.method.<anonymous closure>'
    Receiver: Closure: (List, Map) => dynamic
    Tried calling: DynamicFieldGetterFactory.method.<anonymous closure>(Instance of 'Foo')
    Found: DynamicFieldGetterFactory.method.<anonymous closure>(args, namedArgs)
    #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:45)
    #1      DirtyCheckingRecord.object= (package:angular/change_detection/dirty_checking_change_detector.dart:465:78)
    #2      _FieldHandler.acceptValue (package:angular/change_detection/watch_group.dart:630:17)
    #3      WatchGroup.addFieldWatch (package:angular/change_detection/watch_group.dart:171:29)
    #4      FieldReadAST.setupWatch (package:angular/change_detection/ast.dart:67:31)
    #5      WatchGroup.watch.<anonymous closure> (package:angular/change_detection/watch_group.dart:144:40)
    #6      _HashMap.putIfAbsent (dart:collection-patch/collection_patch.dart:124)
    #7      WatchGroup.watch (package:angular/change_detection/watch_group.dart:143:27)
    #8      Scope.watch (package:angular/core/scope.dart:240:31)
    #9      main.<anonymous closure>.<anonymous closure>.<anonymous closure> (/Users/chirayu/work/angular.dart/test/core/scope_spec.dart:1308:24)
    #10     _LocalInstanceMirror._invoke (dart:mirrors-patch/mirrors_impl.dart:440)
    #11     _LocalInstanceMirror.invoke (dart:mirrors-patch/mirrors_impl.dart:436)
    #12     _LocalClosureMirror.apply (dart:mirrors-patch/mirrors_impl.dart:466)
    #13     DynamicInjector.invoke (package:di/dynamic_injector.dart:97:20)
    #14     _SpecInjector.inject (package:angular/mock/test_injection.dart:58:22)
    #15     inject.<anonymous closure> (package:angular/mock/test_injection.dart:100:44)
    #16     _rootRun (dart:async/zone.dart:723)
    #17     _ZoneDelegate.run (dart:async/zone.dart:453)
    #18     _CustomizedZone.run (dart:async/zone.dart:663)
    #19     runZoned (dart:async/zone.dart:954)
    #20     _syncOuter.<anonymous closure> (package:angular/mock/zone.dart:227:22)
    #21     _withSetup.<anonymous closure> (/Users/chirayu/work/angular.dart/test/jasmine_syntax.dart:13:14)
    #22     _run.<anonymous closure> (package:unittest/src/test_case.dart:102:27)
    #23     _rootRunUnary (dart:async/zone.dart:730)
    #24     _ZoneDelegate.runUnary (dart:async/zone.dart:462)
    #25     _CustomizedZone.runUnary (dart:async/zone.dart:667)
    #26     _Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:488)
    #27     _Future._propagateToListeners (dart:async/future_impl.dart:571)
    #28     _Future._completeWithValue (dart:async/future_impl.dart:331)
    #29     _Future._asyncComplete.<anonymous closure> (dart:async/future_impl.dart:393)
    #30     _rootRun (dart:async/zone.dart:723)
    #31     _ZoneDelegate.run (dart:async/zone.dart:453)
    #32     _CustomizedZone.run (dart:async/zone.dart:663)
    #33     _BaseZone.runGuarded (dart:async/zone.dart:574)
    #34     _BaseZone.bindCallback.<anonymous closure> (dart:async/zone.dart:599)
    #35     _asyncRunCallbackLoop (dart:async/schedule_microtask.dart:23)
    #36     _asyncRunCallback (dart:async/schedule_microtask.dart:32)
    #37     _handleMutation (file:///Volumes/data/b/build/slave/dartium-mac-full-dev/build/src/dart/tools/dom/src/native_DOMImplementation.dart:588)

    DECLARED AT:#0      inject (package:angular/mock/test_injection.dart:97:5)
    #1      _injectify (/Users/chirayu/work/angular.dart/test/_specs.dart:236:25)
    #2      iit (/Users/chirayu/work/angular.dart/test/_specs.dart:244:53)
    #3      main.<anonymous closure>.<anonymous closure> (/Users/chirayu/work/angular.dart/test/core/scope_spec.dart:1305:10)
    #4      describe.<anonymous closure> (/Users/chirayu/work/angular.dart/test/jasmine_syntax.dart:62:9)
    #5      group (package:unittest/unittest.dart:396:9)
    #6      describe (/Users/chirayu/work/angular.dart/test/jasmine_syntax.dart:60:15)
    #7      describe (/Users/chirayu/work/angular.dart/test/_specs.dart:248:46)
    #8      main.<anonymous closure> (/Users/chirayu/work/angular.dart/test/core/scope_spec.dart:1009:13)
    #9      describe.<anonymous closure> (/Users/chirayu/work/angular.dart/test/jasmine_syntax.dart:62:9)
    #10     group (package:unittest/unittest.dart:396:9)
    #11     describe (/Users/chirayu/work/angular.dart/test/jasmine_syntax.dart:60:15)
    #12     describe (/Users/chirayu/work/angular.dart/test/_specs.dart:248:46)
    #13     main (/Users/chirayu/work/angular.dart/test/core/scope_spec.dart:14:11)
    #14     main.<anonymous closure> (http://localhost:8765/__adapter_dart_unittest.dart:169:15)
    #15     _rootRun (dart:async/zone.dart:723)
    #16     _ZoneDelegate.run (dart:async/zone.dart:453)
    #17     _CustomizedZone.run (dart:async/zone.dart:663)
    #18     runZoned (dart:async/zone.dart:954)
    #19     main (http://localhost:8765/__adapter_dart_unittest.dart:146:11)

    #0      _SpecInjector.inject (package:angular/mock/test_injection.dart:60:7)
    #1      inject.<anonymous closure> (package:angular/mock/test_injection.dart:100:44)
    #2      _rootRun (dart:async/zone.dart:723)
    #3      _rootRun (dart:async/zone.dart:724)
    #4      _rootRun (dart:async/zone.dart:724)
    #5      _ZoneDelegate.run (dart:async/zone.dart:453)
    #6      _CustomizedZone.run (dart:async/zone.dart:663)
    #7      runZoned (dart:async/zone.dart:954)
    #8      _syncOuter.<anonymous closure> (package:angular/mock/zone.dart:227:22)
    #9      _withSetup.<anonymous closure> (/Users/chirayu/work/angular.dart/test/jasmine_syntax.dart:13:14)
    #10     _withSetup.<anonymous closure> (/Users/chirayu/work/angular.dart/test/jasmine_syntax.dart:14:5)
    #11     _withSetup.<anonymous closure> (/Users/chirayu/work/angular.dart/test/jasmine_syntax.dart:14:5)
    #12     _run.<anonymous closure> (package:unittest/src/test_case.dart:102:27)
    #13     _rootRunUnary (dart:async/zone.dart:730)
    #14     _ZoneDelegate.runUnary (dart:async/zone.dart:462)
    #15     _CustomizedZone.runUnary (dart:async/zone.dart:667)
    #16     _Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:488)
    #17     _Future._propagateToListeners (dart:async/future_impl.dart:571)
    #18     _Future._completeWithValue (dart:async/future_impl.dart:331)
    #19     _Future._asyncComplete.<anonymous closure> (dart:async/future_impl.dart:393)
    #20     _rootRun (dart:async/zone.dart:723)
    #21     _ZoneDelegate.run (dart:async/zone.dart:453)
    #22     _CustomizedZone.run (dart:async/zone.dart:663)
    #23     _BaseZone.runGuarded (dart:async/zone.dart:574)
    #24     _BaseZone.bindCallback.<anonymous closure> (dart:async/zone.dart:599)
    #25     _asyncRunCallbackLoop (dart:async/schedule_microtask.dart:23)
    #26     _asyncRunCallback (dart:async/schedule_microtask.dart:32)
    #27     _handleMutation (file:///Volumes/data/b/build/slave/dartium-mac-full-dev/build/src/dart/tools/dom/src/native_DOMImplementation.dart:588)

Closes #999