Remove toString() overrides in dart:ui/package:flutter in profile/release mode on wasm/vm targets (#144763)

The flutter engine & framework can opt out of this optimization for
individual classes / class hierarchies via:

  * `@pragma(flutter:keep-to-string)`
  * `@pragma(flutter:keep-to-string-in-subtypes)`

Or by using the convenience constant `@keepToString` from `dart:ui`.

=> This aligns the build process more with g3 (which already does this)

Closes https://github.com/flutter/flutter/issues/52759

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

@@ -258,6 +258,7 @@ class Dart2WasmTarget extends Dart2WebTarget {
       decodeDartDefines(environment.defines, kDartDefines),
     );
 
+    assert(buildMode == BuildMode.release || buildMode == BuildMode.profile);
     final List<String> compilationArgs = <String>[
       artifacts.getArtifactPath(Artifact.engineDartBinary, platform: TargetPlatform.web_javascript),
       'compile',
@@ -265,6 +266,8 @@ class Dart2WasmTarget extends Dart2WebTarget {
       '--packages=.dart_tool/package_config.json',
       '--extra-compiler-option=--dart-sdk=$dartSdkPath',
       '--extra-compiler-option=--platform=$platformFilePath',
+      '--extra-compiler-option=--delete-tostring-package-uri=dart:ui',
+      '--extra-compiler-option=--delete-tostring-package-uri=package:flutter',
       if (compilerConfig.renderer == WebRendererMode.skwasm) ...<String>[
         '--extra-compiler-option=--import-shared-memory',
         '--extra-compiler-option=--shared-memory-max-pages=32768',

packages/flutter_tools/lib/src/compile.dart

@@ -183,11 +183,15 @@ List<String> buildModeOptions(BuildMode mode, List<String> dartDefines) =>
             '-Ddart.vm.profile=true',
           if (!dartDefines.any((String define) => define.startsWith('dart.vm.product')))
             '-Ddart.vm.product=false',
+          '--delete-tostring-package-uri=dart:ui',
+          '--delete-tostring-package-uri=package:flutter',
           ...kDartCompilerExperiments,
         ],
       BuildMode.release => <String>[
           '-Ddart.vm.profile=false',
           '-Ddart.vm.product=true',
+          '--delete-tostring-package-uri=dart:ui',
+          '--delete-tostring-package-uri=package:flutter',
           ...kDartCompilerExperiments,
         ],
       _ => throw Exception('Unknown BuildMode: $mode')

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

@@ -36,6 +36,8 @@ const List<String> _kDart2WasmLinuxArgs = <String> [
   '--packages=.dart_tool/package_config.json',
   '--extra-compiler-option=--dart-sdk=Artifact.engineDartSdkPath.TargetPlatform.web_javascript',
   '--extra-compiler-option=--platform=HostArtifact.webPlatformKernelFolder/dart2wasm_platform.dill',
+  '--extra-compiler-option=--delete-tostring-package-uri=dart:ui',
+  '--extra-compiler-option=--delete-tostring-package-uri=package:flutter',
 ];
 
 void main() {

packages/flutter_tools/test/general.shard/compile_batch_test.dart

@@ -200,6 +200,8 @@ void main() {
           '--no-print-incremental-dependencies',
           '-Ddart.vm.profile=true',
           '-Ddart.vm.product=false',
+          '--delete-tostring-package-uri=dart:ui',
+          '--delete-tostring-package-uri=package:flutter',
           '--no-link-platform',
           '--aot',
           '--tfa',
@@ -248,6 +250,8 @@ void main() {
           '--no-print-incremental-dependencies',
           '-Ddart.vm.profile=false',
           '-Ddart.vm.product=true',
+          '--delete-tostring-package-uri=dart:ui',
+          '--delete-tostring-package-uri=package:flutter',
           '--no-link-platform',
           '--aot',
           '--tfa',

packages/flutter_tools/test/general.shard/compile_test.dart

@@ -105,11 +105,15 @@ void main() {
   testWithoutContext('buildModeOptions removes matching profile define in profile mode', () {
     expect(buildModeOptions(BuildMode.profile, <String>['dart.vm.profile=true']), <String>[
       '-Ddart.vm.product=false',
+      '--delete-tostring-package-uri=dart:ui',
+      '--delete-tostring-package-uri=package:flutter',
     ]);
   });
 
   testWithoutContext('buildModeOptions removes both matching profile and release define in profile mode', () {
     expect(buildModeOptions(BuildMode.profile, <String>['dart.vm.profile=false', 'dart.vm.product=true']), <String>[
+      '--delete-tostring-package-uri=dart:ui',
+      '--delete-tostring-package-uri=package:flutter',
     ]);
   });
 }