Fix analyzer errors

Author: elliette

dwds/test/fixtures/context.dart

@@ -208,7 +208,6 @@ class TestContext {
         workingDirectory: project.absolutePackageDirectory,
       );
 
-      ExpressionCompiler? expressionCompiler;
       AssetReader assetReader;
       Stream<BuildResults> buildResults;
       RequireStrategy requireStrategy;
@@ -274,7 +273,6 @@ class TestContext {
                 experiments: experiments,
                 canaryFeatures: canaryFeatures,
               );
-              expressionCompiler = ddcService;
             }
 
             requireStrategy = BuildRunnerRequireStrategyProvider(
@@ -330,10 +328,6 @@ class TestContext {
               filePathToServe,
             );
 
-            if (enableExpressionEvaluation) {
-              expressionCompiler = webRunner.expressionCompiler;
-            }
-
             basePath = webRunner.devFS.assetServer.basePath;
             assetReader = webRunner.devFS.assetServer;
             _assetHandler = webRunner.devFS.assetServer.handleRequest;