Ensure flutter run build is done in incremental mode. (#107184)

* Ensure build is done in incremental mode.

This allows for faster bootstrapping of the compiler from previously created dill file.

Fixes flutter/flutter#107183

* Avoid initializeFromDill in aot mode

* Update tests

Author: aam

packages/flutter_tools/lib/src/build_system/targets/common.dart

@@ -226,6 +226,8 @@ class KernelSnapshot extends Target {
       trackWidgetCreation: trackWidgetCreation && buildMode != BuildMode.release,
       targetModel: targetModel,
       outputFilePath: environment.buildDir.childFile('app.dill').path,
+      initializeFromDill: buildMode.isPrecompiled ? null :
+          environment.buildDir.childFile('app.dill').path,
       packagesPath: packagesFile.path,
       linkPlatformKernelIn: forceLinkPlatform || buildMode.isPrecompiled,
       mainPath: targetFileAbsolute,

packages/flutter_tools/lib/src/compile.dart

@@ -315,6 +315,7 @@ class KernelCompiler {
         fileSystemScheme,
       ],
       if (initializeFromDill != null) ...<String>[
+        '--incremental',
         '--initialize-from-dill',
         initializeFromDill,
       ],

packages/flutter_tools/test/general.shard/build_system/targets/common_test.dart

@@ -257,6 +257,9 @@ void main() {
         '$build/app.dill',
         '--depfile',
         '$build/kernel_snapshot.d',
+        '--incremental',
+        '--initialize-from-dill',
+        '$build/app.dill',
         '--verbosity=error',
         'file:///lib/main.dart',
       ], stdout: 'result $kBoundaryKey\n$kBoundaryKey\n$kBoundaryKey $build/app.dill 0\n'),
@@ -295,6 +298,9 @@ void main() {
         '$build/app.dill',
         '--depfile',
         '$build/kernel_snapshot.d',
+        '--incremental',
+        '--initialize-from-dill',
+        '$build/app.dill',
         '--verbosity=error',
         'file:///lib/main.dart',
       ], stdout: 'result $kBoundaryKey\n$kBoundaryKey\n$kBoundaryKey $build/app.dill 0\n'),
@@ -348,6 +354,9 @@ void main() {
         '$build/app.dill',
         '--depfile',
         '$build/kernel_snapshot.d',
+        '--incremental',
+        '--initialize-from-dill',
+        '$build/app.dill',
         '--verbosity=error',
         'file:///lib/main.dart',
       ], stdout: 'result $kBoundaryKey\n$kBoundaryKey\n$kBoundaryKey /build/653e11a8e6908714056a57cd6b4f602a/app.dill 0\n'),