Repository: flutter
Issue: TextEditingController strange behavior on the listener
Labels: a: text input,framework,f: material design,has reproducible steps,found in release: 3.3,found in release: 3.7,team-design,triaged-design

Hi,

since the last stable 1.20.2 release, the listener of the TextEditingController has a strange behavior.
- on the first input, the listener is called twice
- when the controller is cleared, the listener is called 3 times. 
  - one with the empty text
  - one with the previous text
  - the last with the empty text again.

## Steps to Reproduce
Code : 
```dart
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key}) : super(key: key);

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  TextEditingController controller = TextEditingController();

  @override
  void initState() {
    super.initState();
    controller.addListener(() {
      print(controller);
      if (controller.selection.baseOffset > 0) {}
      if (controller.text.length == 3) {
        controller.clear();
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            TextFormField(
              controller: controller,
              decoration: InputDecoration(hintText: 'input'),
            ),
          ],
        ),
      ),
    );
  }
}
```

**Expected results on 1.17.5**
```
I/flutter ( 3162): TextEditingController#9066a(TextEditingValue(text: ┤├, selection: TextSelection(baseOffset: 0, extentOffset: 0, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1)))
I/flutter ( 3162): TextEditingController#9066a(TextEditingValue(text: ┤0├, selection: TextSelection(baseOffset: 1, extentOffset: 1, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1)))
I/flutter ( 3162): TextEditingController#9066a(TextEditingValue(text: ┤00├, selection: TextSelection(baseOffset: 2, extentOffset: 2, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1)))
I/flutter ( 3162): TextEditingController#9066a(TextEditingValue(text: ┤000├, selection: TextSelection(baseOffset: 3, extentOffset: 3, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1)))
I/flutter ( 3162): TextEditingController#9066a(TextEditingValue(text: ┤├, selection: TextSelection(baseOffset: -1, extentOffset: -1, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1)))
D/dalvikvm( 3162): GC_CONCURRENT freed 352K, 14% free 3264K/3780K, paused 2ms+0ms, total 4ms
````

**Actual results on 1.20.2**
```
I/flutter (25307): TextEditingController#83c21(TextEditingValue(text: ┤├, selection: TextSelection(baseOffset: 0, extentOffset: 0, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1)))
I/flutter (25307): TextEditingController#83c21(TextEditingValue(text: ┤0├, selection: TextSelection(baseOffset: 1, extentOffset: 1, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: 0, end: 1)))
I/flutter (25307): TextEditingController#83c21(TextEditingValue(text: ┤0├, selection: TextSelection(baseOffset: 1, extentOffset: 1, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1)))
I/flutter (25307): TextEditingController#83c21(TextEditingValue(text: ┤00├, selection: TextSelection(baseOffset: 2, extentOffset: 2, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1)))
I/flutter (25307): TextEditingController#83c21(TextEditingValue(text: ┤000├, selection: TextSelection(baseOffset: 3, extentOffset: 3, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1)))
I/flutter (25307): TextEditingController#83c21(TextEditingValue(text: ┤├, selection: TextSelection(baseOffset: -1, extentOffset: -1, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1)))
I/flutter (25307): TextEditingController#83c21(TextEditingValue(text: ┤000├, selection: TextSelection(baseOffset: -1, extentOffset: -1, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1)))
I/flutter (25307): TextEditingController#83c21(TextEditingValue(text: ┤├, selection: TextSelection(baseOffset: -1, extentOffset: -1, affinity: TextAffinity.downstream, isDirectional: false), composing: TextRange(start: -1, end: -1)))

```