Eliminate support for Dart 1 in AOT snapshotter (#21388)

packages/flutter_tools/lib/src/base/build.dart

@@ -75,7 +75,6 @@ class AOTSnapshotter {
     @required String mainPath,
     @required String packagesPath,
     @required String outputPath,
-    @required bool previewDart2,
     @required bool buildSharedLibrary,
     IOSArch iosArch,
     List<String> extraGenSnapshotOptions = const <String>[],
@@ -130,13 +129,11 @@ class AOTSnapshotter {
       '--embedder_entry_points_manifest=$vmEntryPoints',
       '--embedder_entry_points_manifest=$ioEntryPoints',
     ];
-    if (previewDart2) {
-      genSnapshotArgs.addAll(<String>[
-        '--reify-generic-functions',
-        '--strong',
-        '--sync-async',
-      ]);
-    }
+    genSnapshotArgs.addAll(<String>[
+      '--reify-generic-functions',
+      '--strong',
+      '--sync-async',
+    ]);
     if (extraGenSnapshotOptions != null && extraGenSnapshotOptions.isNotEmpty) {
       printTrace('Extra gen_snapshot options: $extraGenSnapshotOptions');
       genSnapshotArgs.addAll(extraGenSnapshotOptions);
@@ -191,7 +188,6 @@ class AOTSnapshotter {
         'buildMode': buildMode.toString(),
         'targetPlatform': platform.toString(),
         'entryPoint': mainPath,
-        'dart2': previewDart2.toString(),
         'sharedLib': buildSharedLibrary.toString(),
         'extraGenSnapshotOptions': extraGenSnapshotOptions.join(' '),
       },

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

@@ -110,7 +110,6 @@ class BuildAotCommand extends BuildSubCommand {
             mainPath: mainPath,
             packagesPath: PackageMap.globalPackagesPath,
             outputPath: outputPath,
-            previewDart2: true,
             buildSharedLibrary: false,
             extraGenSnapshotOptions: argResults[FlutterOptions.kExtraGenSnapshotOptions],
           ).then((int buildExitCode) {
@@ -141,7 +140,6 @@ class BuildAotCommand extends BuildSubCommand {
           mainPath: mainPath,
           packagesPath: PackageMap.globalPackagesPath,
           outputPath: outputPath,
-          previewDart2: true,
           buildSharedLibrary: argResults['build-shared-library'],
           extraGenSnapshotOptions: argResults[FlutterOptions.kExtraGenSnapshotOptions],
         );

packages/flutter_tools/test/base/build_test.dart

@@ -146,7 +146,6 @@ void main() {
         packagesPath: '.packages',
         outputPath: outputPath,
         buildSharedLibrary: false,
-        previewDart2: true,
       ), isNot(equals(0)));
     }, overrides: contextOverrides);
 
@@ -159,7 +158,6 @@ void main() {
         packagesPath: '.packages',
         outputPath: outputPath,
         buildSharedLibrary: false,
-        previewDart2: true,
       ), isNot(0));
     }, overrides: contextOverrides);
 
@@ -172,7 +170,6 @@ void main() {
         packagesPath: '.packages',
         outputPath: outputPath,
         buildSharedLibrary: false,
-        previewDart2: true,
       ), isNot(0));
     }, overrides: contextOverrides);
 
@@ -198,7 +195,6 @@ void main() {
         packagesPath: '.packages',
         outputPath: outputPath,
         buildSharedLibrary: false,
-        previewDart2: true,
         iosArch: IOSArch.armv7,
       );
 
@@ -245,7 +241,6 @@ void main() {
         packagesPath: '.packages',
         outputPath: outputPath,
         buildSharedLibrary: false,
-        previewDart2: true,
         iosArch: IOSArch.arm64,
       );
 
@@ -293,7 +288,6 @@ void main() {
         packagesPath: '.packages',
         outputPath: outputPath,
         buildSharedLibrary: false,
-        previewDart2: true,
       );
 
       expect(genSnapshotExitCode, 0);
@@ -345,7 +339,6 @@ void main() {
         packagesPath: '.packages',
         outputPath: outputPath,
         buildSharedLibrary: false,
-        previewDart2: true,
       );
 
       expect(genSnapshotExitCode, 0);
@@ -392,7 +385,6 @@ void main() {
         packagesPath: '.packages',
         outputPath: outputPath,
         buildSharedLibrary: false,
-        previewDart2: true,
         iosArch: IOSArch.armv7,
       );
 
@@ -439,7 +431,6 @@ void main() {
         packagesPath: '.packages',
         outputPath: outputPath,
         buildSharedLibrary: false,
-        previewDart2: true,
         iosArch: IOSArch.arm64,
       );
 
@@ -474,7 +465,6 @@ void main() {
         packagesPath: '.packages',
         outputPath: outputPath,
         buildSharedLibrary: true,
-        previewDart2: true,
       );
 
       expect(genSnapshotExitCode, isNot(0));
@@ -506,7 +496,6 @@ void main() {
         packagesPath: '.packages',
         outputPath: outputPath,
         buildSharedLibrary: false,
-        previewDart2: true,
       );
 
       expect(genSnapshotExitCode, 0);
@@ -558,7 +547,6 @@ void main() {
         packagesPath: '.packages',
         outputPath: outputPath,
         buildSharedLibrary: false,
-        previewDart2: true,
       );
 
       expect(genSnapshotExitCode, 0);