Wait for stopApp to complete before proceeding with the app install/run flow (#5412)

packages/flutter_tools/lib/src/commands/run.dart

@@ -237,14 +237,10 @@ Future<int> startApp(
   if (stop) {
     if (package != null) {
       printTrace("Stopping app '${package.name}' on ${device.name}.");
-      // We don't wait for the stop command to complete.
-      device.stopApp(package);
+      await device.stopApp(package);
     }
   }
 
-  // Allow any stop commands from above to start work.
-  await new Future<Duration>.delayed(Duration.ZERO);
-
   // TODO(devoncarew): This fails for ios devices - we haven't built yet.
   if (install && device is AndroidDevice) {
     printStatus('Installing $package to $device...');

packages/flutter_tools/lib/src/run.dart

@@ -137,13 +137,9 @@ class RunAndStayResident extends ResidentRunner {
     // TODO(devoncarew): Move this into the device.startApp() impls.
     if (_package != null) {
       printTrace("Stopping app '${_package.name}' on ${device.name}.");
-      // We don't wait for the stop command to complete.
-      device.stopApp(_package);
+      await device.stopApp(_package);
     }
 
-    // Allow any stop commands from above to start work.
-    await new Future<Duration>.delayed(Duration.ZERO);
-
     // TODO(devoncarew): This fails for ios devices - we haven't built yet.
     if (device is AndroidDevice) {
       printTrace('Running install command.');