Enable lint prefer asserts in initializer lists (#12903) * enable lint prefer_asserts_in_initializer_lists * enable --assert-initializer

diff --git a/packages/flutter_tools/lib/src/application_package.dart b/packages/flutter_tools/lib/src/application_package.dart
index 7f0e687..ad41013 100644
--- a/packages/flutter_tools/lib/src/application_package.dart
+++ b/packages/flutter_tools/lib/src/application_package.dart

@@ -21,9 +21,8 @@
   /// Package ID from the Android Manifest or equivalent.
   final String id;
 
-  ApplicationPackage({ @required this.id }) {
-    assert(id != null);
-  }
+  ApplicationPackage({ @required this.id })
+    : assert(id != null);
 
   String get name;
 
@@ -46,10 +45,9 @@
     String id,
     @required this.apkPath,
     @required this.launchActivity
-  }) : super(id: id) {
-    assert(apkPath != null);
-    assert(launchActivity != null);
-  }
+  }) : assert(apkPath != null),
+       assert(launchActivity != null),
+       super(id: id);
 
   /// Creates a new AndroidApk from an existing APK.
   factory AndroidApk.fromApk(String applicationBinary) {

diff --git a/packages/flutter_tools/lib/src/base/build.dart b/packages/flutter_tools/lib/src/base/build.dart
index dcb4ad1..0f92167 100644
--- a/packages/flutter_tools/lib/src/base/build.dart
+++ b/packages/flutter_tools/lib/src/base/build.dart

@@ -21,9 +21,8 @@
 
 /// A snapshot build configuration.
 class SnapshotType {
-  SnapshotType(this.platform, this.mode) {
-    assert(mode != null);
-  }
+  SnapshotType(this.platform, this.mode)
+    : assert(mode != null);
 
   final TargetPlatform platform;
   final BuildMode mode;

diff --git a/packages/flutter_tools/lib/src/base/flags.dart b/packages/flutter_tools/lib/src/base/flags.dart
index 8007266..a6b750f 100644
--- a/packages/flutter_tools/lib/src/base/flags.dart
+++ b/packages/flutter_tools/lib/src/base/flags.dart

@@ -17,9 +17,8 @@
 /// the Flutter tool (immediately after the arguments have been parsed in
 /// [FlutterCommandRunner]) and is available via the [flags] global property.
 class Flags {
-  Flags(this._globalResults) {
-    assert(_globalResults != null);
-  }
+  Flags(this._globalResults)
+    : assert(_globalResults != null);
 
   final ArgResults _globalResults;
 

diff --git a/packages/flutter_tools/lib/src/base/logger.dart b/packages/flutter_tools/lib/src/base/logger.dart
index 8770efa..053012b 100644
--- a/packages/flutter_tools/lib/src/base/logger.dart
+++ b/packages/flutter_tools/lib/src/base/logger.dart

@@ -177,8 +177,8 @@
 }
 
 class VerboseLogger extends Logger {
-  VerboseLogger(this.parent) {
-    assert(terminal != null);
+  VerboseLogger(this.parent)
+    : assert(terminal != null) {
     stopwatch.start();
   }
 

diff --git a/packages/flutter_tools/lib/src/commands/build_apk.dart b/packages/flutter_tools/lib/src/commands/build_apk.dart
index 63c757d..2041908 100644
--- a/packages/flutter_tools/lib/src/commands/build_apk.dart
+++ b/packages/flutter_tools/lib/src/commands/build_apk.dart

@@ -21,9 +21,7 @@
     this.password,
     this.keyAlias,
     @required this.keyPassword,
-  }) {
-    assert(keystore != null);
-  }
+  }) : assert(keystore != null);
 
   final String keystore;
   final String password;

diff --git a/packages/flutter_tools/lib/src/commands/drive.dart b/packages/flutter_tools/lib/src/commands/drive.dart
index d0d67ad..fe62bf8 100644
--- a/packages/flutter_tools/lib/src/commands/drive.dart
+++ b/packages/flutter_tools/lib/src/commands/drive.dart

@@ -297,7 +297,7 @@
     ..add('-rexpanded');
   final String dartVmPath = fs.path.join(dartSdkPath, 'bin', 'dart');
   final int result = await runCommandAndStreamOutput(
-    <String>[dartVmPath]..addAll(args),
+    <String>[dartVmPath]..addAll(dartVmFlags)..addAll(args),
     environment: <String, String>{ 'VM_SERVICE_URL': observatoryUri }
   );
   if (result != 0)

diff --git a/packages/flutter_tools/lib/src/compile.dart b/packages/flutter_tools/lib/src/compile.dart
index 7d4912f..d2b6607 100644
--- a/packages/flutter_tools/lib/src/compile.dart
+++ b/packages/flutter_tools/lib/src/compile.dart

@@ -104,8 +104,8 @@
 /// The wrapper is intended to stay resident in memory as user changes, reloads,
 /// restarts the Flutter app.
 class ResidentCompiler {
-  ResidentCompiler(this._sdkRoot) {
-    assert(_sdkRoot != null);
+  ResidentCompiler(this._sdkRoot)
+    : assert(_sdkRoot != null) {
     // This is a URI, not a file path, so the forward slash is correct even on Windows.
     if (!_sdkRoot.endsWith('/'))
       _sdkRoot = '$_sdkRoot/';

diff --git a/packages/flutter_tools/lib/src/dart/sdk.dart b/packages/flutter_tools/lib/src/dart/sdk.dart
index 64f128d..c8d6fe9 100644
--- a/packages/flutter_tools/lib/src/dart/sdk.dart
+++ b/packages/flutter_tools/lib/src/dart/sdk.dart

@@ -11,6 +11,9 @@
   return fs.path.join(Cache.flutterRoot, 'bin', 'cache', 'dart-sdk');
 }
 
+/// The required Dart language flags
+const List<String> dartVmFlags = const <String>['--assert-initializer'];
+
 /// Return the platform specific name for the given Dart SDK binary. So, `pub`
 /// ==> `pub.bat`.  The default SDK location can be overridden with a specified
 /// [sdkLocation].

diff --git a/packages/flutter_tools/lib/src/flutter_manifest.dart b/packages/flutter_tools/lib/src/flutter_manifest.dart
index b1bff4b..c909ee6 100644
--- a/packages/flutter_tools/lib/src/flutter_manifest.dart
+++ b/packages/flutter_tools/lib/src/flutter_manifest.dart

@@ -102,11 +102,10 @@
 }
 
 class Font {
-  Font(this.familyName, this.fontAssets) {
-    assert(familyName != null);
-    assert(fontAssets != null);
-    assert(fontAssets.isNotEmpty);
-  }
+  Font(this.familyName, this.fontAssets)
+    : assert(familyName != null),
+      assert(fontAssets != null),
+      assert(fontAssets.isNotEmpty);
 
   final String familyName;
   final List<FontAsset> fontAssets;
@@ -123,9 +122,8 @@
 }
 
 class FontAsset {
-  FontAsset(this.asset, {this.weight, this.style}) {
-    assert(asset != null);
-  }
+  FontAsset(this.asset, {this.weight, this.style})
+    : assert(asset != null);
 
   final String asset;
   final int weight;

diff --git a/packages/flutter_tools/lib/src/protocol_discovery.dart b/packages/flutter_tools/lib/src/protocol_discovery.dart
index 8a8b5cb..1bc35d3 100644
--- a/packages/flutter_tools/lib/src/protocol_discovery.dart
+++ b/packages/flutter_tools/lib/src/protocol_discovery.dart

@@ -18,9 +18,9 @@
     this.portForwarder,
     this.hostPort,
     this.defaultHostPort,
-  }) : _prefix = '$serviceName listening on ' {
-    assert(logReader != null);
-    assert(portForwarder == null || defaultHostPort != null);
+  }) : assert(logReader != null),
+       assert(portForwarder == null || defaultHostPort != null),
+       _prefix = '$serviceName listening on ' {
     _deviceLogSubscription = logReader.logLines.listen(_handleLine);
   }
 

diff --git a/packages/flutter_tools/lib/src/test/flutter_platform.dart b/packages/flutter_tools/lib/src/test/flutter_platform.dart
index 21630ea..86f5bf1 100644
--- a/packages/flutter_tools/lib/src/test/flutter_platform.dart
+++ b/packages/flutter_tools/lib/src/test/flutter_platform.dart

@@ -88,9 +88,7 @@
     this.startPaused,
     this.explicitObservatoryPort,
     this.host,
-  }) {
-    assert(shellPath != null);
-  }
+  }) : assert(shellPath != null);
 
   final String shellPath;
   final TestWatcher watcher;