[dart2wasm] Add --extra-compiler-option to dart compile wasm command

By allowing a pass-through of arbitrary arguments to the dart2wasm
compiler we allow flutter to use options which

* aren't relevant for end-users of `dart compile wasm`
  (e.g. such as providing different platform dill file)

* we may break at any point in time (though in coordination with
  flutter)

Issue https://github.com/dart-lang/sdk/issues/54675

Change-Id: I7da2b69a8c642f8bfaa6546bf9c1a6c3833d55fa
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/349720
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>

pkg/dartdev/lib/src/commands/compile.dart

@@ -516,6 +516,12 @@ class CompileWasmCommand extends CompileSubcommandCommand {
         valueHelp: 'page count',
         hide: !verbose,
       )
+      ..addMultiOption(
+        'extra-compiler-option',
+        abbr: 'E',
+        help: 'An extra option to pass to the dart2wasm compiler.',
+        hide: !verbose,
+      )
       ..addOption(
         'optimization-level',
         abbr: 'O',
@@ -590,6 +596,7 @@ class CompileWasmCommand extends CompileSubcommandCommand {
     final sdkPath = path.absolute(sdk.sdkPath);
     final packages = args[packagesOption.flag];
     final defines = args[defineOption.flag] as List<String>;
+    final extraCompilerOptions = args['extra-compiler-option'] as List<String>;
 
     int? maxPages;
     if (args['shared-memory'] != null) {
@@ -632,6 +639,7 @@ class CompileWasmCommand extends CompileSubcommandCommand {
       // Then we pass flags that were opted into explicitly.
       if (args['name-section']) '--name-section',
       if (args['minify']) '--minify',
+      ...extraCompilerOptions,
 
       path.absolute(sourcePath),
       outputFile,