Remove Compiler.assembledCode.

pkg/dart2js_incremental/lib/dart2js_incremental.dart

Index: pkg/dart2js_incremental/lib/dart2js_incremental.dart
diff --git a/pkg/dart2js_incremental/lib/dart2js_incremental.dart b/pkg/dart2js_incremental/lib/dart2js_incremental.dart
index b78716d4a03be92e09f7e69f2ca62d1a98960085..cada67c2a12b6b7b44f7413a6dab1db506b35e25 100644
--- a/pkg/dart2js_incremental/lib/dart2js_incremental.dart
+++ b/pkg/dart2js_incremental/lib/dart2js_incremental.dart
@@ -5,6 +5,7 @@
 library dart2js_incremental;
 
 import 'dart:async' show
+    EventSink,
     Future;
 
 import 'dart:profiler' show
@@ -72,6 +73,9 @@ class IncrementalCompiler {
     if (inputProvider == null) {
       throw new ArgumentError('inputProvider is null.');
     }
+    if (outputProvider == null) {
+      throw new ArgumentError('outputProvider is null.');
+    }
     if (diagnosticHandler == null) {
       throw new ArgumentError('diagnosticHandler is null.');
     }