Finish strong mode cleaning of dart2js.

pkg/compiler/lib/src/js_emitter/full_emitter/class_emitter.dart

Index: pkg/compiler/lib/src/js_emitter/full_emitter/class_emitter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/full_emitter/class_emitter.dart b/pkg/compiler/lib/src/js_emitter/full_emitter/class_emitter.dart
index 97d244e75234fcd3004b71934f58d9bd9e251f9a..2a2d94411b6d5519cd844981b6aeaefbadb17731 100644
--- a/pkg/compiler/lib/src/js_emitter/full_emitter/class_emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/full_emitter/class_emitter.dart
@@ -125,7 +125,7 @@ class ClassEmitter extends CodeEmitterHelper {
       fields = container.staticFieldsForReflection;
     }
 
-    var fieldMetadata = [];
+    var fieldMetadata = <jsAst.Expression>[];
     bool hasMetadata = false;
     bool fieldsAdded = false;
 
@@ -144,7 +144,7 @@ class ClassEmitter extends CodeEmitterHelper {
       // accessors at runtime.
       bool needsFieldsForConstructor = !emitStatics && !classIsNative;
       if (needsFieldsForConstructor || needsAccessor) {
-        var metadata =
+        dynamic metadata =
             task.metadataCollector.buildFieldMetadataFunction(fieldElement);
         if (metadata != null) {
           hasMetadata = true;