diff --git a/pkg/frontend_server/lib/frontend_server.dart b/pkg/frontend_server/lib/frontend_server.dart
index 139e557..2c45796c 100644
--- a/pkg/frontend_server/lib/frontend_server.dart
+++ b/pkg/frontend_server/lib/frontend_server.dart
@@ -10,7 +10,11 @@
 
 import 'package:args/args.dart';
 import 'package:dev_compiler/dev_compiler.dart'
-    show DevCompilerTarget, ExpressionCompiler, parseModuleFormat;
+    show
+        DevCompilerTarget,
+        ExpressionCompiler,
+        parseModuleFormat,
+        ProgramCompiler;
 
 // front_end/src imports below that require lint `ignore_for_file`
 // are a temporary state of things until frontend team builds better api
@@ -631,7 +635,7 @@
     final sourceMapsFileSink = sourceMapsFile.openWrite();
     final metadataFileSink =
         emitDebugMetadata ? metadataFile.openWrite() : null;
-    await _bundler.compile(
+    final kernel2JsCompilers = await _bundler.compile(
         results.classHierarchy,
         results.coreTypes,
         results.loadedLibraries,
@@ -639,6 +643,7 @@
         manifestFileSink,
         sourceMapsFileSink,
         metadataFileSink);
+    cachedProgramCompilers.addAll(kernel2JsCompilers);
     await Future.wait([
       sourceFileSink.close(),
       manifestFileSink.close(),
@@ -806,6 +811,12 @@
     }
   }
 
+  /// Program compilers per module.
+  ///
+  /// Produced suring initial compilation of the module to JavaScript,
+  /// cached to be used for expression compilation in [compileExpressionToJs].
+  final Map<String, ProgramCompiler> cachedProgramCompilers = {};
+
   @override
   Future<Null> compileExpressionToJs(
       String libraryUri,
@@ -822,7 +833,7 @@
       reportError('JavaScript bundler is null');
       return;
     }
-    if (!_bundler.compilers.containsKey(moduleName)) {
+    if (!cachedProgramCompilers.containsKey(moduleName)) {
       reportError('Cannot find kernel2js compiler for $moduleName.');
       return;
     }
@@ -833,13 +844,13 @@
     _processedOptions.ticker
         .logMs('Compiling expression to JavaScript in $moduleName');
 
-    var kernel2jsCompiler = _bundler.compilers[moduleName];
+    final kernel2jsCompiler = cachedProgramCompilers[moduleName];
     Component component = _generator.lastKnownGoodComponent;
     component.computeCanonicalNames();
 
     _processedOptions.ticker.logMs('Computed component');
 
-    var expressionCompiler = new ExpressionCompiler(
+    final expressionCompiler = new ExpressionCompiler(
       _compilerOptions,
       parseModuleFormat(_options['dartdevc-module-format'] as String),
       errors,
@@ -848,10 +859,10 @@
       component,
     );
 
-    var procedure = await expressionCompiler.compileExpressionToJs(
+    final procedure = await expressionCompiler.compileExpressionToJs(
         libraryUri, line, column, jsFrameValues, expression);
 
-    var result = errors.length > 0 ? errors[0] : procedure;
+    final result = errors.length > 0 ? errors[0] : procedure;
 
     // TODO(annagrin): kernelBinaryFilename is too specific
     // rename to _outputFileName?
diff --git a/pkg/frontend_server/lib/src/javascript_bundle.dart b/pkg/frontend_server/lib/src/javascript_bundle.dart
index 346b4d8..9829c57 100644
--- a/pkg/frontend_server/lib/src/javascript_bundle.dart
+++ b/pkg/frontend_server/lib/src/javascript_bundle.dart
@@ -29,8 +29,7 @@
       this.emitDebugMetadata = false,
       this.soundNullSafety = false,
       String moduleFormat})
-      : compilers = <String, ProgramCompiler>{},
-        _moduleFormat = parseModuleFormat(moduleFormat ?? 'amd') {
+      : _moduleFormat = parseModuleFormat(moduleFormat ?? 'amd') {
     _summaries = <Component>[];
     _summaryUris = <Uri>[];
     _moduleImportForSummary = <Uri, String>{};
@@ -64,7 +63,6 @@
   final PackageConfig _packageConfig;
   final bool useDebuggerModuleNames;
   final bool emitDebugMetadata;
-  final Map<String, ProgramCompiler> compilers;
   final ModuleFormat _moduleFormat;
   final bool soundNullSafety;
 
@@ -75,7 +73,7 @@
   Map<Uri, Component> _uriToComponent;
 
   /// Compile each component into a single JavaScript module.
-  Future<void> compile(
+  Future<Map<String, ProgramCompiler>> compile(
       ClassHierarchy classHierarchy,
       CoreTypes coreTypes,
       Set<Library> loadedLibraries,
@@ -88,6 +86,7 @@
     var metadataOffset = 0;
     final manifest = <String, Map<String, List<int>>>{};
     final Set<Uri> visited = <Uri>{};
+    final Map<String, ProgramCompiler> kernel2JsCompilers = {};
 
     final importToSummary = Map<Library, Component>.identity();
     final summaryToModule = Map<Component, String>.identity();
@@ -150,9 +149,8 @@
       // so it can map dart symbols to js symbols
       // [issue 40273](https://github.com/dart-lang/sdk/issues/40273)
 
-      // program compiler is used by ExpressionCompiler to evaluate expressions
-      // on demand
-      compilers[moduleName] = compiler;
+      // Save program compiler to reuse for expression evaluation.
+      kernel2JsCompilers[moduleName] = compiler;
 
       final moduleUrl = urlForComponentUri(moduleUri);
       String sourceMapBase;
@@ -201,6 +199,8 @@
       };
     }
     manifestSink.add(utf8.encode(json.encode(manifest)));
+
+    return kernel2JsCompilers;
   }
 }
 
diff --git a/pkg/frontend_server/test/src/javascript_bundle_test.dart b/pkg/frontend_server/test/src/javascript_bundle_test.dart
index 26a7c21..02cd813 100644
--- a/pkg/frontend_server/test/src/javascript_bundle_test.dart
+++ b/pkg/frontend_server/test/src/javascript_bundle_test.dart
@@ -106,8 +106,14 @@
     final metadataSink = _MemorySink();
     final coreTypes = CoreTypes(testComponent);
 
-    await javaScriptBundler.compile(ClassHierarchy(testComponent, coreTypes),
-        coreTypes, {}, codeSink, manifestSink, sourcemapSink, metadataSink);
+    final compilers = await javaScriptBundler.compile(
+        ClassHierarchy(testComponent, coreTypes),
+        coreTypes,
+        {},
+        codeSink,
+        manifestSink,
+        sourcemapSink,
+        metadataSink);
 
     final Map manifest = json.decode(utf8.decode(manifestSink.buffer));
     final String code = utf8.decode(codeSink.buffer);
@@ -122,6 +128,9 @@
 
     // verify source map url is correct.
     expect(code, contains('sourceMappingURL=c.dart.lib.js.map'));
+
+    // verify program compilers are created.
+    expect(compilers.keys, equals([urlForComponentUri(library.importUri)]));
   });
 
   test('converts package: uris into /packages/ uris', () async {