eliminate sky snapshot (#8631)

* eliminate sky snapshot

* roll engine

bin/internal/engine.version

-f9c1f5fa539fdfcbcae65a1dd09d1d05949da459
+6e54f5e31f084d2e54a510959f68b89e4d2fdffd
\ No newline at end of file

packages/flutter_tools/lib/src/artifacts.dart

@@ -18,7 +18,6 @@ enum Artifact {
   dartVmEntryPointsAndroidTxt,
   genSnapshot,
   skyShell,
-  skySnapshot,
   snapshotDart,
   flutterFramework,
   vmSnapshotData,
@@ -43,8 +42,6 @@ String _artifactToFileName(Artifact artifact) {
       return 'dart_vm_entry_points_android.txt';
     case Artifact.genSnapshot:
       return 'gen_snapshot';
-    case Artifact.skySnapshot:
-      return 'sky_snapshot';
     case Artifact.skyShell:
       return 'sky_shell';
     case Artifact.snapshotDart:
@@ -144,18 +141,17 @@ class CachedArtifacts extends Artifacts {
 
   String _getHostArtifactPath(Artifact artifact, TargetPlatform platform) {
     switch (artifact) {
+      case Artifact.genSnapshot:
+        // For script snapshots any gen_snapshot binary will do. Returning gen_snapshot for
+        // android_arm in profile mode because it is available on all supported host platforms.
+        return _getAndroidArtifactPath(artifact, TargetPlatform.android_arm, BuildMode.profile);
       case Artifact.skyShell:
-      case Artifact.skySnapshot:
         if (platform == TargetPlatform.windows_x64)
           throw new UnimplementedError('Artifact $artifact not available on platfrom $platform.');
-        continue returnResourcePath;
-      case Artifact.genSnapshot:
+        continue fallThrough;
+      fallThrough:
       case Artifact.vmSnapshotData:
       case Artifact.isolateSnapshotData:
-        if (platform != TargetPlatform.windows_x64)
-          throw new UnimplementedError('Artifact $artifact not available on platfrom $platform.');
-        continue returnResourcePath;
-      returnResourcePath:
       case Artifact.icudtlDat:
         final String engineArtifactsPath = cache.getArtifactDirectory('engine').path;
         final String platformDirName = getNameForTargetPlatform(platform);
@@ -228,8 +224,6 @@ class LocalEngineArtifacts extends Artifacts {
         return _genSnapshotPath(platform);
       case Artifact.skyShell:
         return _skyShellPath(platform);
-      case Artifact.skySnapshot:
-        return _skySnapshotPath();
       case Artifact.isolateSnapshotData:
       case Artifact.vmSnapshotData:
         return fs.path.join(engineOutPath, 'gen', 'flutter', 'lib', 'snapshot', _artifactToFileName(artifact));
@@ -256,13 +250,6 @@ class LocalEngineArtifacts extends Artifacts {
     return fs.path.join(engineOutPath, clang, _artifactToFileName(Artifact.genSnapshot));
   }
 
-  String _skySnapshotPath() {
-    final String clangPath = fs.path.join(engineOutPath, 'clang_x64', _artifactToFileName(Artifact.skySnapshot));
-    if (fs.isFileSync(clangPath))
-      return clangPath;
-    return fs.path.join(engineOutPath, _artifactToFileName(Artifact.skySnapshot));
-  }
-
   String _skyShellPath(TargetPlatform platform) {
     if (getCurrentHostPlatform() == HostPlatform.linux_x64) {
       return fs.path.join(engineOutPath, _artifactToFileName(Artifact.skyShell));

packages/flutter_tools/lib/src/flx.dart

@@ -8,7 +8,6 @@ import 'artifacts.dart';
 import 'asset.dart';
 import 'base/common.dart';
 import 'base/file_system.dart';
-import 'base/platform.dart';
 import 'base/process.dart';
 import 'build_info.dart';
 import 'dart/package_map.dart';
@@ -33,52 +32,6 @@ Future<int> createSnapshot({
   String snapshotPath,
   String depfilePath,
   String packages
-}) {
-  if (platform.isWindows) {
-    return _creteScriptSnapshotWithGenSnapshot(
-        mainPath: mainPath,
-        snapshotPath: snapshotPath,
-        depfilePath: depfilePath,
-        packages: packages
-    );
-  }
-  return _createScriptSnapshotWithSkySnapshot(
-      mainPath: mainPath,
-      snapshotPath: snapshotPath,
-      depfilePath: depfilePath,
-      packages: packages
-  );
-}
-
-Future<int> _createScriptSnapshotWithSkySnapshot({
-  String mainPath,
-  String snapshotPath,
-  String depfilePath,
-  String packages
-}) {
-  assert(mainPath != null);
-  assert(snapshotPath != null);
-  assert(packages != null);
-  final String snapshotterPath = artifacts.getArtifactPath(Artifact.skySnapshot);
-
-  final List<String> args = <String>[
-    snapshotterPath,
-    '--packages=$packages',
-    '--snapshot=$snapshotPath'
-  ];
-  if (depfilePath != null) {
-    args.add('--depfile=$depfilePath');
-    args.add('--build-output=$snapshotPath');
-  }
-  args.add(mainPath);
-  return runCommandAndStreamOutput(args);
-}
-
-Future<int> _creteScriptSnapshotWithGenSnapshot({
-  String mainPath,
-  String snapshotPath,
-  String depfilePath,
-  String packages
 }) {
   assert(mainPath != null);
   assert(snapshotPath != null);