Emulator not being shown in the toolbar.

## Screenshot

Sometimes, the emulator is shown in the toolbar, sometimes it is not shown. However there had been no times, when simulator is not shown. Simulator is always there.

## Flutter doctor
[✓] Flutter (Channel beta, v1.0.1-pre.1, on Mac OS X 10.14 18A389, locale en-GB)
• Flutter version 1.0.1-pre.1 at /flutter
• Framework revision 2f60afca7a (3 weeks ago), 2018-12-29 14:11:09 +0530
• Engine revision 7375a0f414
• Dart version 2.1.0 (build 2.1.0-dev.9.4 f9ebf21297)

[✓] Android toolchain - develop for Android devices (Android SDK 28.0.3)
• Android SDK at /Users/chocolate/Library/Android/sdk
• Android NDK location not configured (optional; useful for native profiling
support)
• Platform android-28, build-tools 28.0.3
• Java binary at: /Applications/Android
Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build
1.8.0_152-release-1248-b01)
• All Android licenses accepted.

[✓] iOS toolchain - develop for iOS devices (Xcode 10.1)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 10.1, Build version 10B61
• ios-deploy 2.0.0
• CocoaPods version 1.5.3

[✓] Android Studio (version 3.3)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin version 31.3.3
• Dart plugin version 182.5124
• Java version OpenJDK Runtime Environment (build
1.8.0_152-release-1248-b01)

[✓] Connected device (1 available)
• Android SDK built for x86 • emulator-5554 • android-x86 • Android 9 (API
28) (emulator)

Reproduce the toolbar behavior using the Flutter doctor environment and connected Android emulator described in the report, then compare it with the always-visible simulator. Start by examining device discovery and toolbar state; done means the emulator is shown consistently while the simulator remains available.

Written by the indexing model from the issue text.