Add flag to enable expression evaluation for web (#55003)

* Add flag to enable expression evaluation for web

Added flag --web-enable-expression-evaluation to flutter run commmand
that enables expression evaluation from IDEs for web target. Disabled
by default.

Helps https://github.com/flutter/flutter/issues/54520

* Update packages/flutter_tools/lib/src/build_runner/resident_web_runner.dart
Co-Authored-By: Jonah Williams <jonahwilliams@google.com>
Co-authored-by: Jonah Williams <jonahwilliams@google.com>

packages/flutter_tools/lib/src/build_runner/resident_web_runner.dart

@@ -418,6 +418,11 @@ class _ResidentWebRunner extends ResidentWebRunner {
           directory: globals.fs.path.join(Cache.flutterRoot, 'packages', 'flutter_tools')
         );
 
+        final ExpressionCompiler expressionCompiler =
+          debuggingOptions.webEnableExpressionEvaluation
+              ? WebExpressionCompiler(device.generator)
+              : null;
+
         device.devFS = WebDevFS(
           hostname: effectiveHostname,
           port: hostPort,
@@ -427,7 +432,7 @@ class _ResidentWebRunner extends ResidentWebRunner {
           buildMode: debuggingOptions.buildInfo.mode,
           enableDwds: _enableDwds,
           entrypoint: globals.fs.file(target).uri,
-          expressionCompiler: WebExpressionCompiler(device.generator),
+          expressionCompiler: expressionCompiler,
         );
         final Uri url = await device.devFS.create();
         if (debuggingOptions.buildInfo.isDebug) {

packages/flutter_tools/lib/src/commands/run.dart

@@ -382,6 +382,7 @@ class RunCommand extends RunCommandBase {
         webEnableExposeUrl: featureFlags.isWebEnabled && boolArg('web-allow-expose-url'),
         webRunHeadless: featureFlags.isWebEnabled && boolArg('web-run-headless'),
         webBrowserDebugPort: browserDebugPort,
+        webEnableExpressionEvaluation: featureFlags.isWebEnabled && boolArg('web-enable-expression-evaluation'),
         vmserviceOutFile: stringArg('vmservice-out-file'),
         // Allow forcing fast-start to off to prevent doing more work on devices that
         // don't support it.

packages/flutter_tools/lib/src/device.dart

@@ -610,6 +610,7 @@ class DebuggingOptions {
     this.webUseSseForDebugProxy = true,
     this.webRunHeadless = false,
     this.webBrowserDebugPort,
+    this.webEnableExpressionEvaluation = false,
     this.vmserviceOutFile,
     this.fastStart = false,
    }) : debuggingEnabled = true;
@@ -639,7 +640,8 @@ class DebuggingOptions {
       hostVmServicePort = null,
       deviceVmServicePort = null,
       vmserviceOutFile = null,
-      fastStart = false;
+      fastStart = false,
+      webEnableExpressionEvaluation = false;
 
   final bool debuggingEnabled;
 
@@ -676,6 +678,9 @@ class DebuggingOptions {
   /// The port the browser should use for its debugging protocol.
   final int webBrowserDebugPort;
 
+  /// Enable expression evaluation for web target
+  final bool webEnableExpressionEvaluation;
+
   /// A file where the vmservice URL should be written after the application is started.
   final String vmserviceOutFile;
   final bool fastStart;

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -199,6 +199,11 @@ abstract class FlutterCommand extends Command<void> {
         '(https://chromedevtools.github.io/devtools-protocol/).',
       hide: true,
     );
+    argParser.addFlag('web-enable-expression-evaluation',
+      defaultsTo: false,
+      help: 'Enables expression evaluation in the debugger.',
+      hide: hide,
+    );
   }
 
   void usesTargetOption() {

packages/flutter_tools/test/integration.shard/test_driver.dart

@@ -448,7 +448,7 @@ class FlutterRunTestDriver extends FlutterTestDriver {
         '--machine',
         '-d',
         if (chrome)
-          ...<String>['chrome', '--web-run-headless']
+          ...<String>['chrome', '--web-run-headless', '--web-enable-expression-evaluation']
         else
           'flutter-tester',
       ],