Repository: flutter
Issue: Selection toolbar/handler should disappear when it is opened and user clicks outside of it
Labels: a: text input,framework,f: material design,a: fidelity,has reproducible steps,P2,found in release: 1.22,found in release: 1.25,found in release: 2.11,team-framework,triaged-framework

## Steps to Reproduce - Issue /1

1. Run the code bellow as mobile-web (or go to this deployed website: https://epic-thompson-badb9e.netlify.app/#/).
2. Select text in the text_field/selectable_text.
3. Tap outside of the text_field/selectable_text

**Expected results:** The selection toolbar/handler should disappear.
**Actual results:** Selection toolbar/handler is still visible and the only way to remove it is to select one of the options in the toolbar.

Note: while reproducing you can notice some unwanted behavior: double tap select text but not show selection toolbar. Let's focus on the actual issue.

![gif](https://user-images.githubusercontent.com/33294549/101696283-308c8700-3a76-11eb-947c-efdfa4cb1556.gif)


## Side Note - issue /2

About the selection toolbar not disappearing reproduces on `stable` and on `master` channel. The toolbar not disappearing on mobile apps does not follow the Material Design rules: https://material.io/design/platform-guidance/android-text-selection-toolbar.html which says:
![Screen Shot 2020-12-09 at 23 51 56](https://user-images.githubusercontent.com/33294549/101698323-929abb80-3a79-11eb-9601-ae3b10f96a37.png)


1. Run the code bellow.
2. Select text in the text_field/selectable_text.
3. Tap outside of the text_field/selectable_text

**Expected results:** The selection toolbar should disappear.
**Actual results:** Selection toolbar is still visible and the only way to remove it is to select one of the options in the toolbar.

![gif](https://user-images.githubusercontent.com/33294549/101697157-94637f80-3a77-11eb-81b6-9d2320464851.gif)


<details><summary>Flutter Code</summary>

```dart
import 'package:flutter/material.dart';

void main() => runApp(SampleWidget());

class SampleWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                TextField(
                  controller: TextEditingController(text: 'Flutter is great\nChange my mind.'),
                  minLines: 3,
                  maxLines: 5,
                ),
                Padding(
                  padding: const EdgeInsets.all(32),
                  child: SelectableText("Flutter is great. Change my mind."),
                ),
              ],
            ),
        ),
      ),
    );
  }
}
```
</details>

<details><summary>flutter doctor -v</summary>

```
[✓] Flutter (Channel master, 1.25.0-5.0.pre.125, on Mac OS X 10.15.7 19H2 darwin-x64, locale en)
    • Flutter version 1.25.0-5.0.pre.125 at /Users/pedromassango/dev/SDKs/flutter_master
    • Framework revision a12e2a473a (18 hours ago), 2020-12-08 23:13:04 -0500
    • Engine revision df39e5c515
    • Dart version 2.12.0 (build 2.12.0-133.0.dev)

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
    • Android SDK at /Users/pedromassango/Library/Android/sdk
    • Platform android-30, build-tools 30.0.2
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 12.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 12.1, Build version 12A7403
    • CocoaPods version 1.9.3

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)

[✓] IntelliJ IDEA Community Edition (version 2020.2.4)
    • IntelliJ at /Applications/IntelliJ IDEA CE.app
    • Flutter plugin version 52.0.4
    • Dart plugin version 202.8070

[✓] VS Code (version 1.51.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.16.0

[✓] Connected device (3 available)
    • sdk gphone x86 arm (mobile) • emulator-5554 • android-x86    • Android 11 (API 30) (emulator)
    • macOS (desktop)             • macos         • darwin-x64     • Mac OS X 10.15.7 19H2 darwin-x64
    • Chrome (web)                • chrome        • web-javascript • Google Chrome 87.0.4280.88

• No issues found!
```
</details>

It is kinda two issues into one but maybe it is fine since they may be solved in the same PR.

Cc @justinmc @chunhtai