[dartdev] Only require wasm-opt binary when compiling optimized wasm.

Passing tool test run: https://ci.chromium.org/ui/p/dart/builders/try.monorepo/flutter-linux-web-tool-tests-try/155/overview

Bug: #61540
Change-Id: I312d71bcb83ba5dd20a50e3934bf962217d1e88a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/450580
Reviewed-by: Alexander Aprelev <[email protected]>
Commit-Queue: Nate Biggs <[email protected]>

Author: natebiggs

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

@@ -901,8 +901,7 @@ class CompileWasmCommand extends CompileSubcommandCommand {
 
     if (!checkArtifactExists(sdk.wasmPlatformDill, warnIfBuildRoot: true) ||
         !checkArtifactExists(sdk.dartAotRuntime) ||
-        !checkArtifactExists(sdk.dart2wasmSnapshot) ||
-        !checkArtifactExists(sdk.wasmOpt)) {
+        !checkArtifactExists(sdk.dart2wasmSnapshot)) {
       return 255;
     }
 
@@ -957,6 +956,10 @@ class CompileWasmCommand extends CompileSubcommandCommand {
     final optimizationLevel = int.parse(args.option('optimization-level')!);
     final runWasmOpt = optimizationLevel >= 1;
 
+    if (runWasmOpt && !checkArtifactExists(sdk.wasmOpt)) {
+      return 255;
+    }
+
     void handleOverride(List<String> flags, String name, bool? value) {
       // If no override provided, default to what -O implies.
       if (value == null) return;