I;ve had this problem for months.
Android Studio 3.2 ( newest version )

Flutter 0.8.2 • channel beta • https://github.com/flutter/flutter.git
Framework • revision 5ab9e70727 (4 weeks ago) • 2018-09-07 12:33:05 -0700
Engine • revision 58a1894a1c
Tools • Dart 2.1.0-dev.3.1.flutter-760a9690c2

Running flutter doctor...
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel beta, v0.8.2, on Mac OS X 10.13.6 17G65, locale en-US)
[✓] Android toolchain - develop for Android devices (Android SDK 28.0.2)
[✓] iOS toolchain - develop for iOS devices (Xcode 10.0)
[✓] Android Studio
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
[✓] Android Studio (version 3.2)
[✓] IntelliJ IDEA Community Edition (version 2018.1)
[✓] VS Code (version 1.27.2)
[✓] Connected devices (2 available)

Observe that Android Studio has teo plugin issues... These plugins are installed and I can still compile for iOS and ANDROID using Flutter. But still looking for a solution on OSx

Solution 1: Amit Kumar

The solution is pretty simple. you have to install the Dart plugin in the android studio.

on Mac:

  1. open Android studio.
  2. Preferences.
  3. plugins.
  4. Browse Repositories.
  5. search for dart and install it.
  6. search for flutter and install it.
  7. restart android studio for changes to take place. Now run flutter doctor and your issue will be resolved.

on Windows and Linux:

  1. The path is File>Settings>Plugins and then the rest of the steps are same as above.

Solution 2: Penny Liu

You can just install the Flutter and Dart plugin in Android Studio by following these steps:

  1. Start Android Studio.
  2. Open plugin preferences (Preferences > Plugins on macOS, File > Settings > Plugins on Windows & Linux).
  3. Select Browse repositories, select the Flutter plugin and click Install.

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  1. Click Yes when prompted to install the Dart plugin.

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  1. Click Restart when prompted.

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Now run Android Studio.

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Run flutter doctor. You should get this output:

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