dart2js: Fix hints in code base.

pkg/compiler/lib/src/ssa/ssa.dart

Index: pkg/compiler/lib/src/ssa/ssa.dart
diff --git a/pkg/compiler/lib/src/ssa/ssa.dart b/pkg/compiler/lib/src/ssa/ssa.dart
index 2bef586a3545a177c69e4ef6991d474c9335074e..a40d75e0677083c940ac6ff8641ea3e58eec2ca1 100644
--- a/pkg/compiler/lib/src/ssa/ssa.dart
+++ b/pkg/compiler/lib/src/ssa/ssa.dart
@@ -11,7 +11,6 @@ import '../constant_system_dart.dart';
 import '../constants/constant_system.dart';
 import '../constants/expressions.dart';
 import '../constants/values.dart';
-import '../deferred_load.dart' show DeferredLoadTask;
 import '../dart2jslib.dart' hide Selector, TypedSelector;
 import '../dart_types.dart';
 import '../elements/elements.dart';
@@ -19,16 +18,13 @@ import '../elements/modelx.dart'
     show ElementX,
          VariableElementX,
          ConstructorBodyElementX;
-import '../helpers/helpers.dart';
-import '../io/source_file.dart';
+
 import '../io/source_information.dart';
 import '../js/js.dart' as js;
 import '../js_backend/js_backend.dart';
 import '../js_emitter/js_emitter.dart' show CodeEmitterTask, NativeEmitter;
 import '../native/native.dart' as native;
 import '../resolution/operators.dart';
-import '../scanner/scannerlib.dart'
-    show PartialFunctionElement, Token, PLUS_TOKEN;
 import '../tree/tree.dart' as ast;
 import '../types/types.dart';
 import '../types/constants.dart' show computeTypeMask;